Do you test one change at a time, or rewrite the whole bit between gigs?

I’m trying to get less chaotic with new material. If a bit half-works, my instinct is to rewrite the setup, swap the punchline and add two tags before the next gig — then if it improves I’ve no idea which change helped. Is it actually useful to change one thing at a time for a few runs, or is that far too scientific for something as room-dependent as stand-up?