I feel much can be learned from looking backwards, here are some examples.
Folk clubs circa 1970 often had upwards of 100 people attending, floor singers had to be able to remember words [without bits of paper]and had to be able to sing in tune and have their instruments in tune.   otherwise they would not be guaranteed a floor spot the next week, there were some excellent resident groups, Skinners Rats for example, a group who I listened to fairly recently, this group had the ability to interact with their audience and understood about performing as well as many professional singers., and did an excellent job as warm up for the main artist
I listened to a live S Rats cd from that time, it sounds like they had 200 people in the audience, and the audience banter was excellent, everyone was clearly having a ball.
around the same time the Singers club were enforcing a rule in their club, which had both positives and negatives, the positives were many revival singers went out and sought out english traditional material and sang it instead of mainly american material, the mistake here was that for a while a lot of good american material was not sung very much, the ideal[imo] would have been the encouragement of both, what the rule said as I remember was that you had to be American to sing American material etc.
folk clubs at that time were run by mainly young people, these young people met got married and many dropped out of going to clubs until their children were grown up, hence a decline in numbers in the late seventies and eighties, it is quite probable that this up and down cycle will occur again and again, what would be interesting to know is how the long running clubs survived the lean years, that would be looking backwards and learning possibly something useful which could be passed on for the future generations of folk music enthusiasts and club organisers.