Seen it a million times, specially at benefits that have called too many performers and they all happened to say yes. Most acts don't intentionally go overtime. More often I think it's due to the organizers not understanding the realities of scheduling: earlier performers get a very relaxed scheduling treatment and may actually be encouraged to go overtime...those naive enough to let themselves be scheduled towards the end of the evening often find themselves playing a shortened set to practically no one.

Also, you shouldn't be too attached to the concept that you will get to play your entire programme just as you rehearsed and planned it. Reality tends to intrude.

A BIG part of handling multi-act shows professionally (for performers and organizers/crew all) is to do everything to ensure that the transitions are made as easy as possible. Performer 1's job is to get packed and offstage as quickly and smoothly as possible--and it helps to talk to the next one coming on. When coming on, it's just as important to let the previous act have time to get their gear clear rather than dumping stuff in their exit path. Play nice, Everybody happy.

W-O