I leave the ones alone that clearly want to be left alone. Their tubs get opened once per day to check for messes. Some others are incredibly docile and start climbing on us as soon as the tubs are open, so they get handled for a few minutes every now and then.
I think that after a certain number of snakes it just becomes unrealistic to expect to handle every single one for a certain amount of time per week. For us, that was like 40 snakes ago.