Are these celebs for real? You know when I read your title I assumed a bath night would be the one day you get to soak yourself in the bathtub for a period of time. I assumed the family took turns in this ritual.
Anyway, I'm not surprised some people don't bath everyday. If they had insufficient water supply that is understandable. If not, then it's nasty having a bath night.
I can't even imagine not bathing once a day. Some days I bath twice, especially during summer.