Almost any live music for dancers can be played as long as needed to suit the occasion. For contras the object is to let all the couples dance with each other so if the sets are long the dance is long & if the sets are short the dance can be shorter.

I've learned some Hungarian dance sequences that used the whole side of an lp 20-25 min. for a set of dances. I understood that in the real village the dance might go on much longer with some sections quite fast & others slower. I've seen the same suite cut down to between 5 & 10 minutes in a performance situation.

I think you're right about the squirm factor & that's why the Hungarian performing groups shortened up what they were doing. Performers also need to vary things much more to keep an audience's attention than is needed in a participatory sitution.

Another example is hymns that used to run to 8-12 verses. Most have been cut to 3-4 & if a hymnal gives more some are usually marked as optional. Sermons are also a lot shorter than they used to be :-)