I've actually started running singarounds recently as well as just taking part in them. The most difficult part I find is timing. You want to make sure that everyone gets a second/third go if possible, but you have to do a mental calculation in your head as to how much time is left and how many people left to have a go.

It can sometimes get upset by things like people doing long songs, people turning up late unexpectedly. When everyone can't get a go on the last round you have to make difficult choices.

Interesting to see it from that side of the fence.