At my local a week or two ago we got to 19 people and that was a squash. We had a new MC on and it was definitely a harsh debut. I didn't even get to perform - just too many people.

I'm surprised you didn't get to perform even one song/tune with that many people, but I suppose it depends on how much time was allowed for the whole session.

The ones at my local folk club, which are by and large OK, tend to last from 8:30 to 11 pm, 2.5 hours. For 20 people that would normally be 7.5 mins each, which would be enough for 1 or 2 songs each, depending on the average length of each song, of course.

Either you must have had a short session, or everybody was singing the proverbial 78-verse Child Ballads! :-)