This question is somewhat abstract, but:
I always hear people talk about “hand synchronization.” But, what are the hands synchronized to? For example, does the left hand (fingering) follow the right (picking)? (If so, what happens with HO/PO or other “legato” techniques?) Or does the right hand follow the left? Or is each hand a slave to the metronome?
For reasons of purity I’m want to hope that each hand follows the metronome and that’s how they work together, but I’m not sure that this is true.