Rack Humidity

I've been wondering this off and on for a while, but I plan to get a rack in the next few months so I thought I should ask. How do people with a rack usually keep tabs on their humidity? Do they just have a hygrometer in one of the tubs in each rack? I can't imagine some with 20 snakes or more have a hygrometer for each snake, I never see one in the videos or pictures I see of peoples snake rooms.

Read the snakes the sheds or lack of will assist in knowing.

If water bowls, vents and thermostat are the same across the board just take humidity from one tub. All others should be about the same

that's what I was thinking sneakysnake