It all depends on your skin type, and how dry or oily your noggin gets.
I haven't shampooed in years. I use an undercoat of olive oil under my gel. That gives a bit of moisture. And usually after my head is dried after the shower I rub a small amount of lotion on the head. The scraping of the razor is enough to clean my head.
If I go a day without a shave I'll just rinse the head with warm water in the shower or at the sink and I'll give it a good towel dry to wipe off any excess moisture. That's all I do, I like to keep it simple.
This is just what I do, hopefully that helps.