Festival sessions when they work can be brilliant affairs and, in my humble opinion, a much more enjoyable experience than the regular pub session both in terms of musical potential and spontaneity.

Conversely, they can often be a disaster, sometimes very patchy and, at other times a complete rabble.

Usually, there is also an increased number of punters around including non performing and often wannabe musicians and singers who want to get get in on the act plus many local people on whose territory these festival sessions are encroaching. Usually, there are even more of the latter too who don't necessarily enjoy the music but like the sense of occasion and opportunity to get "p-ss-d".

Generally, festival sessions tend to be more welcoming and less cliquish than the regular affairs but the downside of this is that many people regard them as a free for all.
While I am more likely to join a session with musicians I don't know at a festival, I still don't force myself upon them or try to take over. Not everyone is quite as good mannered or as reticent as me though.

Another example of bad manners is when a group of musicians and or singers enter a bar and set up their own session while there is another already in progress just a few feet away. As far as I'm concerned, the people who were there first should be allowed to have priority no matter how bad or good they might be. If the new people wish to play or sing, they should either respectfully request to join the existing session or wait until it is over. Sounds sensible, I'd have thought?

As regards sessions organised by the folk festival itself, I would tend to disagree that these are necessarily always a good thing and I think their efforts should be better spent on planning concerts and more official events rather than running pub sessions. Also, I am not keen on the idea of musicians being "planted" in bars although the idea, I'm sure, is to make sure something happens. However, if this is the case, they should be prepared to take a back seat and allow others a chance but some of them just seem to treat it like another gig.