Strategy "Guyton-Klinger" (guardrails)

Guyton-Klinger (2006) is a dynamic strategy with guardrails: the withdrawal is adjusted when the effective withdrawal rate deviates strongly from the initial rate. That way you benefit from good market years (more spending) and protect yourself in bad ones (cutbacks).

Specifically: every year, the current withdrawal rate is compared with the initial rate (planned withdrawal / wealth at the start of FIRE). With a strong deviation, two rules apply. The original model has four — the other two concern the inflation adjustment and the order of sales and are not modeled here.