We all have full time jobs, so limited time, as well.. but, you just take it one song at a time.. and the songs we play are all songs we've known by heart since the 70's and 80's.. I mean, you can pretty much sing your favorite songs in the shower right now, so you KNOW how the songs go.. its just a matter of learning the right chords and notes..
You learn one at a time and just keep adding.. pretty soon you have 100 songs in your setlist.. I get it that that seems like it would be hard to keep up with, but it really isn't.. not that you don't occasionally brain fart onstage - it happens..
I have friends who are actors - we see them in long, drawn out plays with pages and pages of speaking parts.. I always wondered how THEY remembered all their lines,s o I finally asked a friend how he did it.. his answer was, "just like you learn 35 songs - one line at a time".. So, I get it..
Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..