I have seen this topic come up in several threads and thought I would try to consolidate things with a thread here. I will start off by referencing an excellent video by anthony.wood of Searchlight Simulations about proper train handling with the CP AC4400 in TS: From this, I infer that you should bail off the independent brake quickly after a set on the train brake. Indeed, the brake cylinder light flashes in this loco until the independent brake is bailed. I also infer that it is OK to place a set on the air brakes and ride it for a while. What loses the air are multiple sets and releases. So, for balanced braking, I either start off with the dynamic or an air set depending on the grade and, if the dynamics alone can't hold the train, try to wind up with a blend of air and dynamics that maintain a steady speed. However, I have no direct experience in the cab, so I could be wrong! For those like me who are always seeking a better understanding of the vagaries of the triple valve, I find that this diagram from a 2018 Trains Magazine article quite helpful in understanding how you can lose air going downgrade with multiple sets and releases if you don't allow the brake cylinder to recharge between sets.