I have four towels to share with two people. My son is 7 and he doesn’t shower every day - he’s on an every other day schedule (though that really needs to change soon…) during the weekday and every day on weekends (because baths are FUN!).
He uses about 1/10th of a towel to dry his hair and it’s back up on the hook. So he uses whatever is dry that moment. Sometimes he prefers to run around naked and air dry. 
I have two sets - one for body, the other for my hair. Works well. A load every week. And re-using washcloth? Uh, never.