How often do you shampoo?

Basically the title. I have an oily scalp and it drives me crazy. I end up washing my hair every other day because it gets greasy so fast. Sometimes, even the day after I shampoo, my hair looks super oily again. It’s even worse if I or someone else touches my hair....it instantly gets greasy.

I’m already using a dermatologist-recommended ketoconazole shampoo and it has helped with dandruff but my scalp and hair still stay oily.

So, I just wanted to know is there someone else like me?