I shower every day, but I don’t use shampoo or conditioner. I “wash” my hair with water alone. This involves wetting my head, then scrubbing my scalp as if I were using shampoo. The scrubbing helps redistribute oils, and remove dirt and dead skin from my hair. I’ve been doing this for about two years. It works best if you have soft water. The minerals in hard water tend to bind to sebum, leaving you with sticky, white, waxy buildup.
Before that, I used baking soda in place of shampoo, which works fine. Before that, I used natural shampoo.