Is it a bad idea to shower with the bathroom door open?
I keep the bathroom door shut and the fan on while showering. I don't want water vapor to migrate back through the bathroom HVAC vent. On leaving I leave the fan on and shut the bathroom door, but come back a short while later, turn off fan and leave door open. My bathroom has not deteriorated in 38 years of my use, during which time it was renovated once.