The standard thought seems to be if you have a coop and a run you need 4 square feet per chicken in the coop and 10 square feet per chicken in the run. But what if you have a chicken tractor that moves and allows them fresh grass constantly? Do these measurements still apply? What if you allow them additional free ranging in addition to this? It seems to me that the more time free ranging they have the less space they would actually need in the run and/or coop. Is there a formula perhaps that says "For X number of hours freeranging reduce square footage in run and coop by Y"?