When we save into tax deferred retirement account we push taxes (on income) into the future.
It would be an interesting stat to compare present day tax savings in the year that the IRA contribution was made to the tax liability on that contribution (and its potential investment growth) over time. The longer that we have for investments to potentially grow the better the potential outcome.
If I pay taxes on $100 at a rate of 20% in the year I earn that income I net $80 after taxes. If instead, I let the $100 grow tax deferred and I remain in a 20% tax bracket in retirement the government stands to collect not only it's initial 20%, but also 20% of any growth that the $100 made. I keep 80%.
It seems to me that the closer one is to withdrawing IRA funds (whether RMD or not) the less impactful (investment success) these tax deferred contributions can potentially be.
In fact, if you were one year away from retirement withdrawals and that $100 tax deferred contribution fell in value to say $50 (that would suck for you) and then it was withdrawn from the IRA, the taxes collected would be halved as well (that would suck for Uncle Sam).
This is why contributions made closer to retirement should be carefully invested on the risk spectrum. Those dollar potentially have less time to grow meaningfully.
Thoughts?

Thanks @Ted,
I like the idea of a GRA (Guaranteed Retirement Account).
Here's an example of allocation and performance of the CT State Pension plans.
https://ott.ct.gov/pensiondocs/fundperf/FundPerformance01312019.pdf
I see a big push back from 401K, 403b, 40-whatever providers to allow the GRA program to shift retirement moneys from their profit centers to State Pension Systems.
Interview also touched on selling at the wrong time (during a market pullback).
How do you avoid selling when markets are down (sequence of return risk)?

FYI: FYI: The retirement crisis is real. 40% of older, middle-class workers and their spouses will fall into poverty or near poverty in retirement. Economist and retirement expert Teresa Ghilarducci says the U.S.’ 40-year experiment with do-it-yourself retirement is seriously flawed, but there are ways to fix it.
Regards,
Ted
Audio Presentation
https://wealthtrack.com/the-do-it-yourself-retirement-system-isnt-working-retirement-pro-teresa-ghilarducci-has-solutions/

"Sens. Rob Portman, R-Ohio, and Ben Cardin, D-Md. ,,, said the original RMD age was set in the 1960s and has not been changed."
That would have been remarkably prescient as IRAs were created in 1974 by ERISA.
Originally there were no RMDs. They were created as part of the Tax Reform Act of 1986.
https://scholarship.law.georgetown.edu/cgi/viewcontent.cgi?article=1049&context=legal
https://www.bnymellon.com/us/en/our-thinking/baby-boomers-and-required-minimum-distributions.jsp
From the latter page:

[W]ith the increase in defined contribution plan assets, there was a growing concern that taxpayers were using these retirement vehicles as a means to accumulate tax-free wealth rather than as a means to ensure an adequate retirement income. To address the issue, the Taw Reform Act of 1986 was passed requiring taxpayers to being taking annual distributions from their tax-deferred defined contribution plans upon reaching the age of 70½.

FYI: When Ron Strobel was an investment adviser in Seattle, many of his clients were Boeing engineers. They loved their jobs and wanted to keep working as long as they could.
But when they reached age 70½, they had to take required minimum distributions from their individual retirement accounts. They didn't like it.
"RMDs are the No. 1 complaint I hear" from people of retirement age, said Mr. Strobel, founder of Retire Sensibly. "I am seeing more and more clients work into their 70s either because they have to or because they just like working. It's ridiculous that the IRS forces them to begin withdrawing from their IRAs when they don't want to or don't need to."
Regards,
Ted
https://www.google.com/search?source=hp&ei=YHqDXLSVMqGXjwSOrILIBA&q=+Legislation+When+clients+work+past+70,+RMDs+are+still+required+—+and+begrudged+&btnK=Google+Search&oq=+Legislation+When+clients+work+past+70,+RMDs+are+still+required+—+and+begrudged+&gs_l=psy-ab.3...3516.3516..4536...0.0..0.64.123.2......0....2j1..gws-wiz.....0.F7mJdAhiPsA

When the median household income is around $60k, how can you expect a high % of people maxing out 401(k)s? $18k would be 30% going to retirement savings - just not going to happen.

I agree with JoJo on this. Criticizing low-income workers for not maxing-out is reminiscent of Wilbur Ross wondering why all those unpaid government workers didn’t simply obtain a loan. :)
Couple thoughts: The IRS allows a generous catch-up provision during a worker’s later years if they failed to max out in early years. I learned of it accidentally through an “overheard” conversation at work. It proved a great way to make up for my lackluster contributions earlier. Folks nearing retirement (age 50+) should look into it. Think it depends on your employer’s willingness to allow it. https://www.kiplinger.com/article/retirement/T047-C001-S001-the-rules-for-making-ira-401-k-catch-up-contributi.html
Second thought: It’s hard to tell exactly what % of one’s disposable income maxing out would take. Remember the tax deferral one receives when contributing at work. When I was working, a buck contributed was costing something like 75 cents out of pocket - give or take.
On the other hand, if you include all the other taxes we pay in addition to income tax (sales tax, car & boat licensing fees, property tax, phone tax, gas tax, tax on alcoholic beverages & tobacco, social security tax, etc) than your disposable income is really much lower than first appears. That would make maxing out a really onerous option for lower wage workers. Heck, it could easily take 30% or even 40% of their disposable income.

Is this surprising to anybody?
When the median household income is around $60k, how can you expect a high % of people maxing out 401(k)s? $18k would be 30% going to retirement savings - just not going to happen.

https://www.heraldtribune.com/news/20190304/stepleman-do-target-date-funds-do-their-job
Buffet recommended these vehicles recently.
We have 10 % in 401k in tdf

Huh?
https://finance.yahoo.com/news/warren-buffett-target-date-funds-arent-way-go-175409855.html
https://mutualfundobserver.com/discuss/discussion/40833/target-date-funds-buffett

Yahoo Finance reader Greg Woodruff from Bakersfield, California asked Warren Buffett, the CEO Berkshire Hathaway (BRK-A, BRK-B), if target date funds are really adding value.
“No, probably not,” Buffett said during a wide-ranging interview with Yahoo Finance’s Andy Serwer. “The S&P 500 Index Fund is the one to use. That’s the one I used in that bet I made for ten years. It’s the one I’ve told the trustee for my wife to put 90% of the funds I leave her in to.”

Also, the idea with target date funds is to use them for substantially all of your assets. If you don't, you're working against the glide path which is designed for your overall portfolio.
Suppose the glide path for your age says you should be 50/50 stocks/bonds and you have 10% in the tdf and 90% in equity funds. Then your mix is 95/5. What's the point of using the tdf? If you want to control the portfolio allocation yourself, it's easier to work with fixed allocation funds than with ones that "glide".

Who is this guy? His arguments against target date funds are lame.

It's easy enough to find out who this guy is:

... He has also written on portfolio risk management for Barron’s Financial Weekly. Additionally, he assists in the management of the investment portfolio of the Community Foundation of Sarasota County.
Dr. Stepleman holds a Ph.D. in Mathematics from the University of Maryland and a B.S. in Physics from the State University of New York at Stony Brook. He has taught at the University of Virginia and Rutgers University. He also spent 20 years at Exxon Research and Engineering Company and seven years with the RCA David Sarnoff Research Center. ...

Some of his arguments do seem lame. For example, on the one hand lamenting that there's not agreement on what a "correct" glide path is; on the other complaining about "one size fits all". There isn't agreement on a correct glide path precisely because one size doesn't fit all. Different glide paths are offered because what is correct for one person is not correct for another.
Some of his points IMHO not lame at all. "Research by Wade Pfau and Michael Kitces suggests a more optimal glide path ramps down even more severely to 10 percent stocks at retirement and then starts increasing the stock holding gradually to 50 percent. Their research indicates this glide path can provide better protection against sequence of return and longevity risks."
Of course I would think this part had substance. I have to. I said the same thing two days ago:
https://mutualfundobserver.com/discuss/discussion/comment/111071/#Comment_111071

When we were in our savings years my wife had a 403b, and we both had IRAs. Neither of us had access to any other savings mode other than (of course) Social Security. We both maxed out our IRAs,and my wife maxed out her 403b (converted to an IRA after her retirement). Any additional spare funds were put into either American Funds or American Century, with no load.
Like Investor, we maxed out whatever was available to us.

Well, it seems like I am one of those in that 13%. There are a lot of people that earn more than me and yet they hardly have any retirement savings. They are spending like there is no tomorrow.

One thing that the study shows (the one in the link) is that there is some momentum effect in periods less than a year. And it is more likely to be momentum of the asset class/sector so those managers that had a larger allocation to that asset class did better. But momentum strategies generate a lot of churn and is not particularly suitable for taxable accounts. Consider following a momentum strategy in a retirement account (be careful some custodies have frequent trading restrictions, you can get banned so investigate before)

Right, the price of success. Look how short the first two close periods were.
Fund Closed to New Accounts: 12/31/2003 - 12/15/2008
Fund Closed to New Accounts: 5/16/2002 - 11/18/2002
Fund Closed to New Accounts: 4/3/1998 - 3/16/1999
Fund Closed to New Accounts: 2/9/1993 - 9/19/1993
Fund Closed to New Accounts: 3/6/1992 - 5/29/1992
I cannot recall when I dove in, and it probably was in retirement accounts only after its start-of-1990 launch date. (JT was ~30, at the outset, can that be?)
August 1990 I did join a company that had a Fidelity-based 401k and I bet that's when it was, or at least an increase if I was already a holder.
But I was paying Fidelity low loads long before then, in various Select funds, in and outside of retirement accounts.
Hard for me to believe now. But the 1980s were this crazy bull market, quite like now, until Oct '87 anyway. (Even then, in hindsight, that recovery was <2y.)

I doubt you bought the fund at inception. It appears that it was a (low) load fund then. In late 1992, Fidelity started waiving some loads in IRAs. The load was not removed on taxable accounts until 2003.
Chicago Tribune, 1990:

At one time only the Fidelity Magellan Fund had a front-end load of 3 percent. Now, almost all of Fidelity`s equity, or stock, funds have at least a 2 percent load.

South Florida Sun Sentinel, 1992https://sun-sentinel.com/news/fl-xpm-1992-11-09-9202280589-story.html:

On Nov. 1, Fidelity dropped the low-load (usually 3 percent) sales charges on all their funds (except Fidelity Magellan and their Select sector funds) for those investing through their retirement accounts, such as IRAs and SEPs. Non-retirement accounts still have to pay the low-load as before.

FLPSX closed shortly thereafter (2/9/1993)
From the 1994 prospectus (the earliest online at SEC):

HOW TO BUY SHARES
ONCE EACH BUSINESS DAY, TWO SHARE PRICES ARE CALCULATED FOR THE FUND: the offering price and the net asset value (NAV). The offering price includes the 3% sales charge, which you pay when you buy shares, unless you qualify for a reduction or waiver as described on page .
WAIVERS. The fund's sales charge will not apply:
1. If you buy shares as part of an employee benefit plan ...
2. To shares in a Fidelity Rollover IRA account purchased with the proceeds of a distribution from an employee benefit plan ...
3. If you are a charitable organization ...
[you get the idea; not waived for retail investors]

From the Sept 26, 2002 supplement to the prospectus:

On June 19, 2003, the Board of Trustees of Fidelity Low-Priced Stock authorized elimination of the fund's 3.00% front-end sales charge. Beginning June 23, 2003, after 4:00 p.m. Eastern time, purchases of shares of the fund will not be subject to a sales charge. Information in this prospectus specific to front-end sales charges for this fund is no longer applicable

By keeping the Investor shares around, and by using those Investor shares in VTTVX, Vanguard is able to collect an extra 0.11% in fees while claiming to have a 0% management fee on VTTVX. This is deceptive.

But Vanguard doesn't claim this at all. On their fund page for VTTVX, they clearly report an expense ratio of 0.13%, which includes the fees of the underlying funds. Nowhere do they claim that they have a 0% fee. Anyone can plainly see that the "Target Retirement" funds like VTTVX are more expensive than the plain index funds -- no deception here.

Ahhh, mid 40's. I was there once.

...when I hit retirement I still expect to still be practically all-in on equities as I am now in my mid-40s. While I won't be 'diversified' across so-called "asset classes" I will be 'diversified' by my own comfort levels,

@rforno , I wouldn't recommend that in retirement without a cash bucket (another asset class), unless you don't need to withdraw from your savings. Withdrawing from a full-in equity portfolio during a bear market could be detrimental to your savings, especially if that bear market is at the start of retirement. So if you had that cash bucket, 1, 3, 5 years, whatever your comfort level is, I think 100% equity for the remaining portfolio is perfectly fine for a risk taker like yourself. Probably do better than most.

And no, I don't care about LC/MC/SC G/B/V designations

I don't disagree with you on this at all, but you know these are not asset classes.

What I am trying to say that many uncomplicated and reasonable strategies will work if given sufficient time for accumulation and growth.

I believe that you and Pfau/Kitces are addressing two different halves of one's investing lifetime. My fault - you had been talking about your investing up to retirement and I tossed in a study of glide paths after retiring.
Put the two halves together and what you wind up with is a U shaped curve for equity exposure - high when young, declining (probably further than the traditional glide path) to retirement, and then rising.
I introduced this for the purpose of illustrating that glide paths (even during accumulation) could do with a bit of scrutiny. For example, as I hinted at above, one might be better off shooting for a lower equity allocation at the target (retirement) date.
They're addressing sequence of return risk in retirement. Since that's an early retirement risk, they find that starting with a low equity allocation deals with that risk, and increasing equity over time compensates for the lower starting point. At least that's what I got from skimming - it's been awhile since I originally read the full writeup.
No question - uncomplicated is good. My portfolio (like almost everyone's, I suspect) falls somewhere between Skeet's three dimensional portfolio and a couch potato portfolio. I'm gradually pruning. This could take many years though. Think half-life - the more the portfolio "decays" (is pruned), the slower the pruning gets.

FWIW saying when I hit retirement I still expect to still be practically all-in on equities as I am now in my mid-40s. While I won't be 'diversified' across so-called "asset classes" I will be 'diversified' by my own comfort levels, sectors, and due diligences. (And no, I don't care about LC/MC/SC G/B/V designations - I buy/own what I feel comfortable owning, not according to any M* or Street recommendation)
But that's ME. Each to their own ... there's no right or wrong here.

@davidrmoran, do you think a fund that holds 98% stocks is a diversified portfolio? In retirement no less!!!

@davidrmoran, do you think a fund that holds 98% stocks is a diversified portfolio? In retirement no less!!!

The question is: what's an appropriate glide path?

I will argue that most decreasing glidepaths do a pretty good job. The end result over time tends to be similar.
I am not sure of the increasing equity allocation in retirement though. I have to study it more. If the market turns south early in the path the recovery is easier with the help of newer contributions plus the person has an option to delay the retirement and adjust to the realities. If that happens after your retirement the impact will be much higher.
Now, I can think of a scenario that you have accumulated sufficient sums for retirement and covered potential risks that you may face in retirement and you have a significant excess in retirement funds. Well, I can consider that part defectively separate from retirement and invest for legacy or for charitable purposes. If the investment works for that portion good. If not well, you don't have to worry, you have already safeguarded yourself. I am sure there exists people in this situation. I don't see myself having too much excess funds for retirement. That is a really good problem to have.
An alternative to glide path is a lifetime fixed allocation say 60/40 like pensions used to invest. That is also a simple and reasonable strategy.
What I am trying to say that many uncomplicated and reasonable strategies will work if given sufficient time for accumulation and growth. The problem is that contributions are too small and starting too late in life. That makes accumulation of funds for retirement difficult. The investor is driven to taking more risk than they would otherwise need because of the lack of time and if they happen to hit a period with markets doing their prolonged nosedive they risk not having enough in retirement. It becomes a gamble rather than long term investing.

I agree with you that a core holding having an appropriate glide path plus a little bit of tweaking around the edges can serve as a good plan for many people.
The question is: what's an appropriate glide path?
See, e.g. Pfau's and Kitces' paper suggesting that one's equity allocation should gradually increase through retirement. Not that most people have the stomach for that.
https://www.onefpa.org/journal/Pages/Reducing Retirement Risk with a Rising Equity Glide Path.aspx
https://www.kitces.com/blog/should-equity-exposure-decrease-in-retirement-or-is-a-rising-equity-glidepath-actually-better/