It doesn’t seem that long ago that shower caps were common so people wouldn’t get their hair wet in the shower - I still see them used in old movies and TV shows. Shampooing was rare. I don’t remember washing my hair much when I was a teenager with a fairly long DA, maybe the grease protected it?
Today I couldn’t go for more than a couple days - my scalp starts itching. If I didn’t use a conditioner I’d never get a brush or comb through it when I got out of the shower.
Oh you won't, but its important to realise that those effects - the itchy scalp, the tangled hair, etc - are a byproduct of the constant washing with harsh detergents. This is because the shampoo, while cleaning your hair, also gets rid of the natural compounds your hair is producing. In effect, the heavy use of shampoo and conditioner means that you have to use even more shampoo and conditioner! If you stopped using shampoo your scalp would itch but the effect would go away in a week or so as the natural compounds were replaced.