I'm curious what kinds of things led you to retire earlier than the 4% rule would have suggested. Is it your investment profile? Something about your future income? Tax cleverness? Something(s) else?
Sure. Vanguard Personal Advisor Services (VPAS) has its own proprietary software, in which they have invested millions to leverage their vast experience. It is Monte Carlo based. It ignores the 4% Rule. Clients go through a planning process to envision all the major pieces of their retirement plan, including Social Security and other expected income sources, debts and mortgages, life expectancies, legacy goals or lack thereof, a healthcare projection tool for each individual based on their specific useage of medical services to date, plans for specific expenses, such as home repairs and travel desires, everyday spending needs per year, etc., etc. You name the topic and Vanguard has an instrument to help you get a handle on it. All of that vast data is factored in.
That said, though the long term goals are protected and kept in sight, VPAS focuses on controlling only five years out, because so many things change short-term. They project what one can spend each year through a program called Dynamic Spending, which leverages Monte Carlo analysis, our known goals and expectations above, our progressively more conservative asset allocation, etc., etc. As market conditions occur, recommended spending year over year might go up a max of 5% or down a max of 2.5%. So, despite the complexity under the hood, the directive to us each year is very doable and simple to understand.
Given all of that, FOR US, our SWR for 2021 is about 7.5%. Hence, RE was possible for me in 2020 rather than 2025 or something. I emphasize FOR US, because we have no heirs and we inputted 95 as our life expectancy. YMMV. VPAS does not consider home equity, so should the SHTF in the out years and our AUM assets fall to zero (which they never will, because we would see it coming years ahead and would adapt) we still have that to rely on, plus maximum SS taken at age 70.
I hope that gives a sense of the program and why, to me, the 4% Rule is a far-too-blunt instrument that, had I followed it, would have kept me yoked to the cart for several more years than necessary rather than FIREing with high (90%+) confidence at age 54.