This seems to be a world wide problem. I used to MC shows and was continually runnimg into this problem and made some bad friends with musicians over this.   However audiences liked my format of aloting and keeping within specific time guidelines. Seems entertainers (espically amateurs) feel that the audience prefers to listem to one individual who feels he is just a little bit superior and not to the rest of the entainers. When I entertain as an individual I time my program to 10 minutes - maximum 15. I feel it is better to leave the stage with the audience wanting more rather than less. In shows, I allotted individuals a time of 15 minutes and groups (dep[ending on how many entertainers) up to 30 minutes.