Kelso (the last time I went there) did guest-first, or sometimes a *very* short floorspot and then the guest. The part that followed the guest could go on till the small hours with the average age of performers and listeners getting steadily younger. There was a usually a bunch of young people with guitars waiting outside for their chance.

I don't see a problem with that. The guest could get to bed at a reasonable hour if they wanted and more people got to play in a more loosened-up setting. Everybody was happy. One of the liveliest clubs I've met with.

This depends on appropriately flexible licencing rules and having no neighbours within earshot.