We sometimes go to a tune/song session (NOT a folk club) at the Shroppie Fly, Audlem. We can only go in the school holidays when the dance club I am involved with doesn't meet, so we don't have a chance to get fed up with any repeated songs. When we started going I was learning to play by ear, and the songs that everyone knew and played along with were a real help, far easier than 'tunes'.
The good thing about that session is the variety, one Boxing Day afternoon the bar was full and we 'played to the gallery' -handing round the percussion, playing In my Liverpool Home, and Whisky in the Jar, and rousing tunes like Susanna and Salmon Tails. The next Monday evening it was quiet, and the musicians were in reflective mood, trying out unfamiliar material.
Both very enjoyable in a different way.

The other problem with over familiar material is that people will probably join in the chorus the way they've always sung it, which may not be the way you intended it to go.