After i finished Lvl 300 3 days after season release… 
I finished lvl 300 farming pits long time ago. If you just do it a couple of hours a day its no problem. Only problem is getting exhausted/mad/depraved etc… Therefore you have to reach a special mental stage where you just play using instinct. Your thoughts are far away at this point thinking about lots of nice things. (PoE2, small fluffy animals, Asmongold, hamburgers)