Rack Systems: Tub sizes, air flow, and humidity questions?

Got my first rack system the other day, and I was wondering what size bins I should have for each size of snake (babies to adults, or their size in Gs)?
Also, how many holes do you guys usually put in the bins for air flow and humidity levels to be okay?
The humidity in my house is around 40-45%, and I currently have 8 quart tubs for my two youngest ball pythons. I drilled out 3 holes on the smaller sides, and 2 holes on the larger sides, and may have to adjust those to suit my home.
But i digress, what works for you guys? What size tubs do you use for the sizes of the snakes? How many holes do you drill per size of the tub?

I use 3'x2'x8" tubs for my females and 22"x16"x6" tubs for my males.

I set the drawer up and check humidity, based on what I get I add holes as needed. I go slow because it is easier to drill a hole in a tub than to jam it up.

I have ended up without any holes in the females' drawers and between 0 and 6 holes in the male drawers.