When you play an RPG, do you have a set party you stick to, or do you use all of them?

I prefer using them all, so I actually kind of dislike it when characters you don't use auto-level with your party because it's less incentive for me to keep them on rotation and I never know who to use! I like having to swap them out.

I'm weird and I always feel like I'm neglecting real people if I don't use everybody (That's also why I have to buy crunchy and smooth peanut butter in rotation as well)

I think my ideal system is when the not used characters get a percentage of the experience, so they don't fall too far behind but it's still reason to use them.

Which do you prefer?