Yeah I agree it is nuts to keep trying to tweak the 4% rule.

I remember someone who used to post under the moniker 'Dory36'. He used to say that using back testing for retirement planning was similar to checking the weather history before you went on a trip. If the odds are that there was little chance of rain, then you wouldn't pack an umbrella. But if it did happen to rain anyway during the trip-- you would make the necessary adjustment (ie buy an umbrella). Same thing with retirement withdrawals.


In addition, if you can live on an initial 4% withdrawal from savings, then that means that your average actual withdrawal rate over time will be < 4%. That's because other income streams come online after retirement. Take me for example. Upon retirement, I plan to withdraw at 3.75% rate from savings. Once I add Social Security to the mix (2-5 years later), savings withdrawal rate drops to 1.5%.