i have regular singers and they know how i run my show, i pretty much stay with my rotation, if their names are already on the playlist, when i call for their names, that's when when they give me the slip with next song they wanted to sing,( it's easier for me to keep track on playlist rotation that way ) and for those who asked about their turn, i usually show them my playlist and show them where they are at on the rotation, and if i get " i'm going home in a few minutes excuse " ( most of the time they just wanna impress some ladies
) i usually tell them to come early next time.. and most of the time they will stay at the duration of the show.