Depends on the style of music dosn’t it? If you are only talking about some chords and singing it should be pretty easy to have a large repertoire. I play various fingerstyle genres and I am struggling to memorise 60 songs. I know 25 in my head but can play many of the other songs off the page. A flamenco guitarist said it was really hard to learn a repertoire well and retain it and added that he had lost most of his. So I would be very happy if I ever reach that target.