i do about 5 good warm up sets with 135, full rep. then 225 full rep, then usually when i get up to 3 plates i do half reps. and i keep going with half reps up to 405-455. i started doing this cause i plateaued real hard with full squats. since i started squatting like this my strength went up drastically both on half squats and full squats. towards the end of my squat workout i lower it bac to 315, and do a couple good sets of full squats.