I'm another who doesn't budget, but tracks overall spending. The classic withdrawal plan increases your annual spending with inflation, but does not adjust to up or down market years. There are two things I don't like about that. If you start off with a prolonged bull market, one of those sequences that Firecalc shows you with a huge end of life balance, it doesn't let you increase your spending. I get the impression that most people work around this by resetting their plan to allow for more spending. But it also doesn't have you decrease your spending if you start with a prolonged bear market or other failure case. My impression is that most people will eventually cut spending in this case, or get a part time job to add some income, but the longer you wait to take action in a failure case, the bigger hole you've put yourself in.
I use VPW (variable percentage withdrawals), which gives me a target spending amount each year, based on the start of the year balance on my investable assets, and a very slightly increasing % to spend. The % increase gives me a bump due to inflation, plus accounts for having less of my lifetime remaining. After a good year, it also gives me a little bit more spending room, and after a bad year it throttles me down a little bit. It's only a little bit, as it spreads the change out over your remaining years.
I like these small adjustments because in a prolonged downturn it immediately starts to reduce my spending target, but it won't be as drastic as it would be if I waited until I was really in trouble before making adjustments. Theoretically VPW never fails, but the reality is that if things go bad enough your % spending may not cover the true essentials for you. I believe that failure should come later (and therefore be less likely) than starting with 3.5 or 4% and increasing spending with inflation each year.