I think tollerance is the ideal as smallpiper has said. I for one run mixed sessions in Sheffield but I am also involved or have been involved in music sessions and sing-a-rounds.I enjoy all aspects of these sessions, I can find it real fun to be playing guitar in a music session but I am primarily a singer. I think looking at it logically most musos don't like the idea of waiting their turn as in the sing-a-round senario so they become ignorant and just blast ahead. It shouldn't be a battle of wills but sometimes can be as happened at Tap and Spile this Whitby Folk Week eventually this bunch of semi ignorant musos left after some time with the words 'you win !!'. We didn't start the conflict but 'they' perceived it as that.