6 planes per day ops-losses isn't really out-of-the-way, but you must adjust your operational tempo so that it's in line w/ replacement plane production & the ability of sqns to accept them. IMO 10-20% rest for your combat sqns is kinda low, especially if they are running continuous ops at 15k' or above. i believe that pilot fatigue contributes to ops-losses, as well as airframe damage/fatigue, so i try to keep the sqns maxed out w/ pilots. 30-40% rest usually works ok for me, but i'll increase that to 50% for long-range or LRcap missions.
my own ops-loss prob centers on the transports flying the Ledo air-bridge, at 50% rest the C-47s were flying into mountains faster than their build-rate. transport pilot exp gain is glacial, & it don't help that ~20% of my ops-losses also gave me a KIA/WIA pilot. changing to 60% rest has stopped the bleeding & allowed a build-up of airframes in the pools, also i'll pay more attention to plane fatigue - when a sqn has used its reserve aircraft, i'll put it on stand down for awhile.
i run supply-transport ops at 6k', is there a better altitude?