About every three days. I just don't want to wash it more than that, so I'm learning how to make it look decent in between washes.
3a/b, F, normal porosity

I've gotten my routine down to the bare essentials, finally
Wash: Suave Tropical Coconut
Leave-in: Suave Everlasting Sunshine, detangle with Denman brush
Gel: LAL Sport or Wet Look
Scrunch with flour sack towel, plop 10 minutes, air dry
Refresh with either plain water or Suave/water mix