*Such* a personal question. As with the same question for before retirement, everyone's answer is going to be different based on risk tolerance, projected expenses/SWR, age a retirement and reasonably expected longevity, health, healthcare coverage in old age, amount of expenses covered by SSI, ability to cut expenses in down markets, and more.
Maybe start by answering those questions, although it's still going to come down to a personal preference, and which risk bothers you more--the risk of losing in a down market, or the risk of inflation/increased expenses associated with age outpacing the growth of your stache.
