Regarding the people who waste time deciding what to sing/play when it's their turn, I've only been guilty of that myself sometimes when I get asked to accompany others, so when it's my turn, I haven't had a chance to think what to do next myself. This especially tends to happen when there aren't many people there so I've already 'used up' the songs I'd planned to do that evening. But I probably only spend a few seconds deciding, and usually plump for one of my old stand-by songs.