The clubs that still manage to book a guest every week are good because they have had to be good to survive. There has been a long decline in this format but the situation seems stable now.

If I look back at when I first started going to clubs as a teenager there were two a week accessible by public transport which meant that I could see two decent pro or semi pro performers a week. From my parent's house there are still two (different) weekly clubs accessible by public transport but each only runs about 1 guest night a month.

On the other hand there are a variety of sessions and singarounds within driving distance and that circuit simply didn't exist back in the 60s.