I do almost exactly the same thing with excellent results. Never have had bugs.I have a few coops. I've had 20 birds in my 8'x10' coop and give it a daily pick up under the roosts every morning after I let the birds out. I use pine shavings also. If I were to leave these shavings in there, adding more up until cleaning once a year, it would be a dusty environment with mites. I do a cleaning once every three months, removing all old shavings from floor and nests, shop vac the whole coop, spray Oxine disinfectant, let dry, then spray a good coat of Gardstar or Ravap over roosts, nests, walls, floor, cracks, and crevices. After it dries and new shavings are added, the birds are allowed back in the coop. Since I started this program years ago, I never have mite or louse infestations or coughing birds.