Isn't it more important for an organiser to decide how to produce a VARIED programme of singing for the audiences rather than how many songs should be allotted to each individual/group.... whatever?
Most groups I have listened to are formulaic and the sound the produce is more less the same for each song - I would be inclined to take a book to read along to any singaround that was going to give me the same sound in twenty minute blocks (sorry Steve).
Research carried out by Charles Parker and others around the time the Radio ballads were made, found that after a surprisingly short time, people stop listening, both to singing and speech. if it is delivered using the same tone, or weight or dynamic; their ears "went to sleep", as Charlie put it.
Far too many of the singaround sessions I have attended, in the UK and here in Ireland, have been boring, not because the singing is bad or the songs aren't interesting (far from it), but because singers perform their songs without having considered that has gone before it comes round to them.
A well sung long ballad can be riveting, two can be OK - three, and it's time to go down to the bar for a pee, a pint and a chat.
An essential aspect of our work in the Critics Group was to be aware of and learn to handle all the different aspects of singing - efforts - tone, etc..... so that all your songs didn't come out sounding the same.
I believe that folk songs are peoples' life experiences versified - as human beings, we experience a whole range of emotions and events - if we delivered them in a monotone, we'd be very boring people.
The same with song.
Jim Carroll