I'm coming at it from a totally different angle, but here ya go.
The way we function is for any event you get a PM (me), lighting person, sound person, and a general
hand who usually plays flyman. Thats just to open the doors. If asked, I can function as your SM, such as calling
rail cues,
house lights, audio cues,
etc. Rarely do I need to do more then
call house lights and larger moves. Usually I
call house lights, float around during the show, then come back to
call house up. If we have a show that either the show carries a crew or brings in their own crew, that is fine, however my same basic 4 guys stay on no matter what. If it means they spend the
call hanging out in the break room listening to com, fine.
So, yes, I do
call the show if asked to. I will also allow others to
call the show if they want to... no matter how poorly they might do it. I will always offer my services but I will vacate my seat just as fast.
As far as what do to during the show if your not calling it and its an outside group... float. Make sure nothing is on fire. Make sure nothing is going to hurt anyone. Make sure that your crew is doing what they need to be doing.