And there should be a time limit for each person. You get some people who sing a three minute song and others regularly go on for fifteen minutes or more.

If fifteen minutes is OK for one performer then it should be the same for everyone.

If the set time is a more reasonable five minutes then people should be held to it. And the person who takes that long chatting to his neighbor, borrowing a tuner and tuning his guitar should be given hearty applause at the end of the five minutes and be informed that his turn is over.