>>713635735 (OP)Industry standard for what? I never seen a game need A and B except to accept and cancel stuff (usually rpgs), and you don't want to overlap your finger over accept and cancel risking pressing one of them by mistake.
Usually action games use Y and X for attacks, and you hold them exacly like the second picture.
Fun fact, if you play super metroid with the original button setup, ideally your thumb would be hovering above X (fire), A (jump) and B (run) so you can press the three simultaneously