OP, why do you ask?…
Mostly just because I thought it might spur some discussion, which it has.
Also, because as I am finalizing my plans for retirement in the next 12-18 months, I’ve had to buckle down and get serious. I want to be able to tell myself that I have looked at my plan from every angle, that I’ve done due diligence. I’m not naïve enough to think that we can plan for all eventualities but I do think we can do our part on the front end to avoid kicking ourselves later for being too cavalier about what is probably the biggest financial (and maybe even psychological) decision in our lives. Maybe second only to marriage. That's a pretty big one, too, I suppose.
In a lot of ways, it’s become clear to me that the "simple math" for retirement is only simple when you’re accumulating assets, but gets more complicated in a hurry when you are in the spending phase.
I don't think that a simple 4% rule really works for most people as an actionable plan. I'm not questioning the math or the validity of the rule itself, but the reality of how we spend money, especially over a multi-decade period. It also doesn't account for things like SS income, which most of us (in the US) will get, even if it's a reduced amount. It's even more important to consider if one is, shall we say, not entering retirement in the flush of youth.
Some strategies, such as the guardrails models, might start with a >4% WR, but the caveat is that historically you would have had to reduce your spending, sometimes severely and for extended periods to make it work. Given the current market, I think it's very probable that a guardrails model would force such a reduction, probably in the not distant future. I’d like to avoid that if I can. I certainly don't want to begin retirement with what I think is a high probability that I'd have to reduce my planned spending, especially in the first years that are supposed to be full of fun and adventure. That's the point of retiring early, after all.
On this forum, and with some of the comments in this thread, I sometimes get the impression that (some) folks aren’t really doing the work to look at what a real retirement withdrawal phase will look like. If you’re still 5-10 or even more years away from retirement that’s fine. So many things will change that it probably wouldn’t be of much value. Maybe that’s because you have, or plan to have, so much money or you spend so little, that you can go with a 2% or 3% rule and be content. I’m sure that would be a safe financial plan, so more power to you.
Some people are relying on 'flexibility' to obviate making detailed plans or decisions. That model doesn't fit my personality. I worry about anyone who just does some hand-wavy "I'll be flexible" thinking about such an important thing.
There are a few responses along the lines of "I'm only spending 1%-2% every year and I can't imagine needing more", or "I cover all of my spending with other income", etc. Now maybe that's something that just happened after retirement because of good market returns. I can understand that. But if that's your actual plan?
When I read that sort of thing, I just can’t help thinking “so what’s the money for, then?”