Martin Ryan ran one in Chippenham a few years back where he had groups of 2 or three people and got them to make lists of words, lists of subjects and talked about the lists for about 1 minute per group and then let us get on with it. The sort of formal entree and the size of the groups were relevant.

Sandra Kerr ran a successful w/s by discussion tactics/methodologies (called "talking") then set a scenario and let us get on with it. I tried to colaborate with a couple of people to no avail - I think it needed the guidance of the workshop host to make that work. FWIW I wrote a complete song in the time left - it was a simple formula but a very worthwhile result nonetheless.

I have done committee songs at w/s and they are not the best - it is the size of the group as much as the personalities.