Some of the best sessions I've been to have been those where musicians don't try to drown out the player leading the set. Simple rule of thumb, if you can't clearly hear the person leading the set, you are playing too loud. Having people voluntarily show respect to players that way avoids all kinds of problems and also lets everyone hear and appreciate the music.

Some of the worst sessions I've been to have been where one or more loud instruments along with thumping feet bully the tune into a different speed and drown out the musician who started the set, sometimes even forcing them to stop.

Bit of common sense all round makes everything go a lot smoother. It;s not a competition or an ego parade. Let the music breathe a bit. Get musicians to think about the overall effect and you've got it sorted.