i wash usually every third day, my hair is super curly and cury hair is prone to dryness, and i find that my hair can usually be washed one night, be worn down for two days as long as the curls don't get too frizzy (i can't brush my hair to fix that), and then be in a ponytail on the first part of wash day. i always wash my hair at night because i find that if i let it dry while i'm asleep, laying on the pillow behind me (never under my head), it gives it a ton of volume and some quirkiness, which i like. during the summer, it's usually every other day because the humidity and heat make it frizzy and oily quicker, but i try to avoid that.