At least every other night, but I try to shower every night. I guess I shower at night since I somehow get very dirty during the day, so seems pointless to shower in the morning, and I will be clean when I got to bed, plus at night I get to stay in for like 15-30min since I wait until about 9pm, when my family goes to bed. Wash my hair every time I shower because if I don't, my hair starts to curl and it looks weird to only have one side of my hair to be curly while my other side is almost straight... maybe after my hair gets longer I will slow down on washing my hair.
Though I am trying to get into a habit of cold showers since it has been really hot lately, and I also didn't enjoy sweating in the shower. I also just like to feel clean and smell good(helps me feel better about myself, better when people tell me I smell good). Oh, and if I don't shower often, I get cysts behind my earlobes, but I have never had to worry about acne much