multiple times for everyone.. either morning, mid-day or evening just before bed.
For me at least Both, morning shower is a quick freshen up, no hair 1 min. max... Evening is hair/shaving..
EVERYONE HAS to shower up before bed.. regardless of how late. unless you are passed out which is rare. But Florida heat, humidity and add in the sun-screen.. Just gross, simply gross to enter my bedsheets.
Kids usually wash their hair mid-afternoon as we usually take a swim... to get clorine out.