OMG I LOVE this thread cause it’s so true. I have 2 teenage boys and both of them will stand in the shower till the hot water runs out. One will come out no cleaner than he went in just wetter.
It got so bad 3 years ago the fan couldn’t vacate the humidity fast enough and it would get this… rain in the bathroom. the condensation would pool on the ceiling and drip all over the place. I put in a switch with a built in humidity controller on it for bathroom fans and installed the largest fan Lowes offered, like 190CFM or something in a average sized bathroom. If I had ST like I do now I’d definitely be using a motion sensor with humidity and temp readings to control fans and lighting.
On a side note when I’ve had enough and they wont get out I revert to plan B. When I installed the water heater it’s normal to install a 1/4 turn ball valve on the cold side for servicing and such. I installed one on the hot side too. More than once I’ve used that valve on the hot side. There is a 12-15 second delay till the last of the hot water travels to the other end of the house then zrip the shower ends very abruptly. Good luck with your project and DO let us know how it turns out.