I find that I can cope with all the types of singaround/session and usually adopt the "when in Rome" philosophy, but at the "jump in" type, I'm conscious of not wanting to take too many turns so I always tend to jump in after the same performer that I did last time around. I don't know if other people tend to do this, in which case there would seem to be some kind of underlying scheme of organisation under the apparently free flowing format.

Cows always go in to be milked in the same order without being prompted, so do us folkies tend to want some kind of system?