Because of mobility issues and the hassle that is getting in of the shower, as well as dry and sensitive skin, I can't do daily showers; I usually shower ever other day or every third day if I can get away with it and clean up in other ways on the days in between. I also only wash my hair every other shower day - any more dries out my scalp, but any less frequently and my dandruff gets awful. It's a fine balancing act.
I usually shower during the day or early evening when I know at least one of my roommates will be home just in case I get stuck or I fall or something, but I really prefer showering at night before bed if I can since a really hot shower can help my muscles relax which means I can fall sleep easier.