The question isn't survival at all, I and I suspect Major Tom believe the numbers.
I do believe the numbers or, to be more accurate, I have a pretty good understanding of what they mean. I was merely wondering - and this is by no means an original thought - how many people would begin a 30, 35 or 40 year withdrawal period with a particular WR, and stick to that exact same WR, with annual adjustments for inflation, for their entire retirement? There may be several different reasons for retirees pulling out different amounts. For instance, quite a lot of people seem comfortable with a WR that gives, say, a 95% chance of success, or the highest WR that will still just give a 100% chance of success. I am not taking issue with those decisions, as everyone has different risk tolerances and intended strategies but let's, for instance, take a retiree who feels comfortable with a WR that Firecalc gives a 95% chance of success. If he/she is unlucky enough to have a poor sequence of returns early on in retirement, then we know that at least historically, he/she can continue following the strategy and won't run out of money. There is, however, a difference between rationally knowing something, and having the emotional make-up to follow-through. I wouldn't mind betting that, after a poor sequence of returns, many folk would reduce their spending a little until the market recovered somewhat.
Likewise, what if our retiree were lucky enough to experience a good sequence of returns (or even an "average" one)? If, after 10 or 15 years, you were to find yourself with considerably more money than you were planning/hoping for, after adjusting for inflation? Perhaps a few would stick to the same WR but I'm betting that at least a few would either increase their withdrawals for a few years, or perhaps reset their strategy, and begin another 30 or 40 year withdrawal period. I bet a few folk here reset every few years - c'mon - own up
All I'm saying is that when at least 30 years have passed since the Trinity study and similar studies that were based on it were carried out, how many retirees will have experienced
an entire retirement with the exact same WR (with adjustments for inflation) throughout the entire period? I can tell you that if I hit paydirt and end up one of those particularly lucky high-flying trajectories in Firecalc, I won't still be living on the same amount (inflation adjusted) as when I started!
PS - I wrote this reply a few hours ago, but it has been sitting on my computer in review mode and un-posted until now because I ended up napping with 2 cats on top of me and couldn't move