Well, I don't do the 4% rule, other than as a general guesstimate at any given time on how much we could retire on today. I do the "bucket" method, where I group future years into specific buckets, based on changes in income/expenses, and then figure out how much I need to have now to fill each bucket at that particular future time.
We ignored SS, pension, and inheritances when we were younger, because those things were uncertain, and we wanted our savings strategy to focus on our worst-case needs. Once we hit about 50, we started adding in maybe 1/2 SS, because historically, Congress has phased in significant changes to SS, so that people who are retired or close to retirement age get hit less than younger folks. Now we're close enough that we're including full SS in the budget -- although we also have a ton of luxury, like travel, that can easily get cut if SS comes in less than anticipated.
Also note that our projections include only one SS after about age 75, rather than 2, because once the first of us dies, that second SS goes away.
