- I'd not thought of that clumps of similar stuff problem. But blimey!! Its a definite danger.

Most definitely. Especially if the people sitting together are lovers of either (a) very long a cappella trad. ballads about making harps out of your lady love's breastbone and stuff, or (b) very long self-written songs with one chord, about one's Feelings - usually in a strange tuning that it takes five minutes for the singer to get into to his/her satisfaction. Three or four of either one in a row can blow an evening - unless that's what everyone there came to hear.

How does the free for all thing work though?

In my experience, it often doesn't.

How does it even itself out - do you need everyone to be equally assertive? And how do you avoid the self-proclaimed-hero type taking over & hogging the session?

In order: As noted above, it often doesn't. Yes, and they never are. You don't, if you forgot to bring a gun or at least Pepper spray or mace.

I'm hopeless at just jumping into a gap - just in case everyone hates me....

I'm very good at it. So everyone hates me. I'm a reforming self-proclaimed hero type. Like a reforming alcoholic. You're never "cured."

Peter.