well thats the issue. if he reverts to whats comfortable there will never be improvement with the princeton. what you speak of, the idea of alternating between PnR and princeton is the goal.
Nash admitted he's still making a conscious effort not to over-rely on what he already knows in favor of using this time to cram in the new stuff.
Nash understands that to win you have to be multiple. have to be varied. running PnR every game and winning a bunch of games is useless because in the playoffs PnR isn't the same. not nearly as effective and defenses tighten up with more rest in between games. you have to have a varied arsenal.
right now it's early. the princeton is just part of the weapon. not the whole weapon. but right now the PnR is the weapon everyone has down. the Princeton isn't. once they get that down you'll probably see a more varied offense. Nash himself understands that reverting to PnR nash ball is just going to stall the growth of the team