every time you wash your hair, you strip it of its natural oils. the more you wash it, the more oil it produces to compensate. subsequently, the less you wash it, the less oily it will eventually become. that's usually the reasoning behind why most people who say they wash their hair every single day "have to" because it'll become unbearably greasy if they don't - well, of course it will, because you're washing it every single day! try using water and just a little bit of soap once in a while instead and see what happens, you'll feel gross at first but you might really be surprised by how naturally soft and shiny your hair eventually ends up being once it sorts itself out. your body's natural oils also operate on a pretty similar set of instructions but again, i exercise just about every day and the stench of my sweaty armpits could feasibly be bottled and used as a chemical weapon so i don't think any amount of not showering could possibly lead to some sort of natural equilibrium for me.
