Will leaving conditioner on your hair longer make it work better? (from The Beauty Brains)

Apparently not (scroll down). I have to admit this sort of blew my mind. My whole shower routine is built around leaving the conditioner on my hair for the maximum amount of time. But when you think about it, it's pretty obvious. Conditioner doesn't actually absorb into your hair; it just coats it. (Unless it's coconut oil, in which case it needs to stay on for longer than your typical shower.) So the most important thing is that you spread the conditioner evenly throughout your hair (or at least the part you want to condition), not that you let it sit.

Sometimes you just absorb that folk wisdom/marketing shit and don't question it. Oops.