[ideamotor]

I'll respond in more detail later but here is a paper that examines it: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2324930:

"Accordingly, as the results support, for those looking to maximize their level of sustainable retirement income, and/or to reduce the potential magnitude of any shortfalls in adverse scenarios, portfolios that start off in the vicinity of 20% to 40% in equities and rise to the level of 60% to 80% in equities generally perform better than static rebalanced portfolios or declining equity glidepaths. Though as the results also reveal, in particular scenarios where the equity risk premium is depressed, the optimal glidepath includes less equity, and in scenarios where the goal is to withdraw at a level that stresses the portfolio and its expected growth rate, higher overall levels of equity are necessary; with such high-risk goals, having a relatively high-risk portfolio, with the danger that entails, is still the optimal solution (and for clients who cannot tolerate that level of risk, the ideal solution is to choose not a less risky portfolio, but a less risky and aggressive goal). Nonetheless, for everyone else looking to maximize a sustainable income level, or determine the amount of assets to support a (reasonable) target income level, rising equity glidepaths appear to both maximize the likelihood of success and sustainable income and reduce the magnitude of shortfalls when they occur."

There is a a lot of discussion of this here: https://www.bogleheads.org/index.php. Also, this article: https://www.kitces.com/blog/should-equity-exposure-decrease-....