I got to the point last year where I realized my hair likes getting washed twice a week. I just went one week without washing and it wasn't bad but I didn't like it. But, like everything else, it's an individual thing. You have to figure out what works for you and your hair.
When I was in high school, I had some friends who didn't wash their hair for 2-3 months. They, and their mothers had jheri curls and they said it kept their hair healthy and made it grow. Which was puzzling because they all had some tore up heads of hair!!! Broken off, damn near bald patches and whatnot!!!