To add to an earlier comment-I, too have watched Tom Lewis come in,(at Mystic Seaport 2 years ago)be recognized, asked to sing, and do a nice number that just fit, then listen to others.

As to Uncle Dave's rhetorical question...I sure wish some of those young people were reading Mudcat so they would realize how controversial their behavior was. If they had a reason, they really should have said.
I have been in workshops (like at the FSGW Getaway) where folks get over committed and promise to do a song to help out a friend, but are expected in another workshop in 10 minutes, so ask to go out of turn and excuse themselves politely.....no problem with this.

All I hope from threads like this is that there is some subliminal conciousness raising among those who 'might' possibly have been less than thoughtful once or twice.