Often enough to keep it from smelling. Some people clean daily which is probably excessive but to each their own. Some of us clean a lot less. There are several different factors.
I usually scrape my droppings board once every two to three weeks or when I expect visitors. Got to clean up for visitors. The last time I cleaned the bedding out of my coop it had been four years. I didn’t need to then but I wanted that stuff on my garden.
Part of it depends on your chicken density. The more chickens you shoehorn into a tiny space, the more often you have to clean. Using a droppings board can greatly reduce the need to clean the whole coop. How much and what kind of bedding you use can make a big difference. The list goes on and on.
A smelly coop or run generally means a wet coop or run. If you can keep them dry, you can greatly reduce the smell problem. Good ventilation helps too. If the poop builds up, it can get thick enough to stay wet and start stinking. Just high humidity in the air can make a difference too.
We have so many different climates, set-ups chicken densities, and management methods that there is no one right answer for each of us. It’s what works for you.