I think I wash my hair with any product once or twice a year, and only if I’ve had something in it (lice warning at kids school, sprayed with mud from a hike or similar) and then literally use a drop of shampoo. The less I wash it the better it looks.

Hair products are a lie. Water and a scrub is way better.

My hair is short. No idea if the same applies to long hair. I suspect it does.