Max out once every 4-6weeks on squats. The main focus of squats is so you have enough leg strength to do your OLifts and to increase them. A fat 1RM isn't going to be all that if you can't get 3reps x 3sets heavy to a high %. In comp you have 3 big Snatches and 3 big C&J. Sometimes you follow yourself so you have to be prepared. If your gassed you can't lift properly/ well due to being let down by your lack of legs.
People get too caught up a fat 1RM. Volume and then build up the heavy weight works better imo.
Most people don't need to squat 6x a week or lift that much. 3x a week on lifts and squats is plenty imo until your clocking over 300 on the sinclair then you can mix it up. But most people are better off with more sleep.
But yeah it's hard to figure when to max out. Just go by how you feel in the gym. Yesterday for instance my body felt pretty beat up from the lack of sleep over 7 days, my bum was hurting from eitehr the hamstring/ glute thing I was doing or the numerous times I stacked it whilst trying to snowboard :P. BUT my lifts were good in my current shape, 110, 115, 118, 120, 125, 130, 130, 130 and then back squat 160x6; 170x4; 180x2. Best session of the year so my legs are getting back in to it!