Horses for courses.

If it's an audience that doesn't have much to do with folk music, they probably want mostly songs they might have come across, helps them feel at home and not excluded. "Give us the Black Velvet Band"

If it's an audience of folkies they're not so likely to want to hear yet another version of some old standard."Not the Black Velvet Band again..."

If it's a performer who's known for some special song, and the audience haven't heard him or her recently singing it, that's what they want to hear.

Or it might be someone known for writing topical stuff, and the audience want to hear whatt they might have done with the latest scandal in the papers.

As I said, horses for courses.