That's true, which is why I usually go with the Rule of 500 (total invested across all assets >= predicted monthly expenses * 500). My rational is a safe withdr

That's true, which is why I usually go with the Rule of 500 (total invested across all assets >= predicted monthly expenses * 500). My rational is a safe withdrawal rate of 3.5%, 25% tax on all withdrawals, and an extra 10% to be on the safe side. This adds up to 500 (12 / 0.035 / 0.75 * 1.1). It's good enough to ballpark it, but it doesn't take into account how tax changes over the years (more gains and less base cost) and between accounts (some can have pretty complicated tax rules that can affect each other), how some accounts become available only later in life (retirement funds), expenses/incomes that aren't fixed, etc etc.