In a small digression from the current points - "what is a session?" Seems to have totally different connotations to my offspring, then in their 20s, when I said I was "going for a session"! They fell about laughing! (Your guess is as good as mine!)
That aside, a session is what you choose to make of it: I go to some where it's strictly "round the room" and others where it's "just jump in", tho' some of us will try to make sure that no-one dominates and even the shrinking violets get a turn if they want one. At most of the sessions I go to there are some who do just come to listen, and appreciate what we do.
Our local pub has had its ups and downs over the years I have been going there (maybe nigh on 20 years now): there has been a session once a month for more than 30 years. The pub has had a number of landlords, and has even been closed and boarded up in between tenancies for periods of up to 6 months. But each time there has been a new incumbent, someone from the local Folk Club has gone in and spoken to the landlord about continuing this tradition of having a session on the first Tuesday of any month. No arrogance involved, just a polite suggestion, which has always been welcomed: the pub would probably be otherwise near empty on that night. Most people live within walking or bussing distance, so the bar sales are good. All of the landlords have appeared to enjoy the music, and the current one employs other groups at the weekends to do folk or jazz nights. There is another bar on the premises for anyone who does NOT want to listen, or prefers to watch football! And there is none of this "we have to keep the TV on, if only on silent" on our session nights.
Living in a big city with lots of international visitors adds another dimension to the folk session scene here: there are some who do specialise in playing the "crowd-pleasers" and "just for the tourists" stuff, whereas others who just "do what we normally do": the latter often draws comments such as "this is the best thing I've seen in your city" and we in turn mutually benefit from the times when foreign visitors have contributed songs or tunes to such sessions.