I played for a short time (!) with a duo of guitarists who:
(1) didn't take it into account that many of the song recorded were played on instruments tuned to Eb, so the players were using chord shapes as E so they emulated the pitch no matter how weird or unlikely the difficulty of playing the chord sequence
(2) both used capos.
(2) they used capos on different frets so they could 'voice the chords differently'
(4) at the end of the day/performance they hadn't a clue what key they were really in as an E shape at the capo was, to them, always an E, so although one was capo'd at the 4the fret it was still E etc
(5) they often changed key of a number between performances as they were mates and practiced together midweek on their own
(6) The key change was often a surprise to me onstage.
As I said, I played with them a short time.....
G.
p.s. Actually, when it was all OK they actually sounded quite good