I have 8 hens in a 8x12 coop. The floor is vinyl over pressure treated lumber planks and I put pine shavings down. It's all one room but one side has the roosts and the other is the "living room" area with the nest boxes, feeder and water. The poopy side is obviously the area under the roosts. So I turn it over and rake it when it starts looking bad and rotate the clean shavings from the living area over to the roost side. The chickens usually stir it up, but sometimes I help with the rake. Then I take fresh shavings and put them down on the living area and nest boxes. It's kind of a rotation of shavings from clean to dirty. The whole place stays nice and dry and I don't have any smell. I know I'm going to have lots of nice mulch in the spring when I start working in the garden. I'm only on my second bale of shavings since I started clean in November. If all goes well, I won't need to empty it all out until spring. Moisture is the big issue. If you can keep it dry in there, it makes a huge difference and the pine shavings really keep things dry. The roost side does get deeper, but it's a benefit because all those used shavings seem to really insulate the floor and keep it warmer, so they're warmer where they sleep.
Lisa