It’s pretty complicated because we are exposed to toxins and air pollutants that our ancestors never had. So removing more than usual might not be that bad. I’ve gone maybe two days without washing my face and my skin was still fine though. A good diet helps a lot. I drink bone broth and eat meat organs full of good vitamins. My hair is a mystery though. It looks great if I don’t wash it for a while but i have some dry skin flakes that fall out. It’s not dandruff though.