If my memory serves me right, I helped build a composting privy at Double Springs Gap with the Rocky Top crew back in the 90's on a snowy October day. When I went by there about 15 years later the privy had been replaced with a newer one. Composting and moldering privies take maintenance by volunteers and cooperation by the users for them to function properly. I have been by many a privy on the AT where there is no duff or wood chips to add when you finished your business. Some privies had a rake and instructions on how to gather duff but I don't think I ever saw another hiker collecting any when the supply was depleted. The ones that use wood chips have to have the chips packed in by trail maintainers. When I thru hiked back in 2010 many privies were beyond capacity down south. I can see why a cat field would be designated.