I don't think there is anything wrong with 5x5 for arms but my own past has made doing that low reps with my body not productive, Too much boxing and baseball built up a lot of scar tissue, going heavy does not stimulate the muscle like higher reps do for myself. My old arm routine that work good was based on 5x5 with chains to get more resisatnce at the top of the move, then 2x8 and 2x12 sets I would really focus on controlled movements, it was almost as the 5x5 sets were warm up.
best I ever did was 5x5 with 285 on close-grip and 135 on barbell curl