How often do you clean?

[Lefitte]

Hey, pretty straight forward here. I'm trying to get a feel of how often everyone does a full large cleaning on their tanks. I dont mean a spot cleaning for poop or cleaning the water dishes and hides and such but a full clean that includes all that and replacing the substrate. I have both a desert species with aspen chips and a tropical species with moss. Both of my snakes are young and small in large cages so it's a bit hard to find their poops. There hasnt been any mold.

So do you do it on a strict schedule? Every month, two months, six months?
Or do you do it by sight, feel, smell depending on when you feel the need to do it? Before this, I used newspaper so it was very easy to throw away full dirty sections and switch out. There is so mucb substrate now that it seems like a waste to dump it all out until I'm sure I need to.