ya man 1.5-2 hours of training with all those sets seems like a lot
even if it feels like you are doing the most for your legs...sometimes less is more
i try to keep it anywhere from 12-16 sets on leg day just cuz i try to squeeze in calves as well
always perform to optimum intensity, ESPECIALLY with legs
however if your successful with your split more power to ya
IMO start with squats first because they are definately one of the best mass builders you can get for your legs
glad your getting results dood keep it up!
get big
get husky!