I agree that once a month is likely enough. There is an elephant in the room however, are you not doing the rack too? If you use lidded tubs this is a moot point. If you don't there is still a contact surface that also needs to be cleaned as well, the rack surface that the snake can contact. It is a bigger job than the tubs. I have been trying to figure out an efficient way to do that one. Due to the liquid I remove the flexwatt each month. It takes me most of a day. I can't imagine how people with larger collections do.