When I started going to folk clubs recently, I only knew a few songs, most of which I had learnt about 40 years previously in my previous venture into folk clubs. I quickly realised that I would have to learn some more songs so I made myself a promise that I would not repeat the same song in any venue for a year. That way I had to start learning songs and I stuck to it, though it was a bit hectic at times. I also managed to get through the year with only using a cheat sheet about two or three times. Now I am in the process of trying to relearn many of the songs I sang and also continuing to learn new songs. I try not to repeat a song I have sung for at least three months.

Even as an amateur I do think you should try and develop a reasonable repertoire and vary what you sing at your regular venue. I may be going to a folk club to sing for my own pleasure, but I am also singing to others so I feel owe it to the other regulars to vary what you sing and to try not to bore them. OTOH if someone asks you to sing a particular song - and it has happened even to me - then I am quite happy to oblige.