tl;dr, sorry :?
wrt/ the "20 songs" question, I spent most of my playing time working on my bands compositions, and never bothered trying to do a note-to-note rendition of the (few) covers we ever did. The only time I played in a (very short-lived) cover band we were still trying to come with our own versions.
To make a long story short: I can play my current band's set list (without any backing tracks I mean), that makes for =~ 20 songs, and I far as I'm concerned that's all I need to know to be considered as a guitarist by my bandmates and, as far as I can tell, by the audience too :mrgreen: