From: Bristol, UK
This is not logical. The UK has Home Guard units that are not in game, and would fulfill the "garrison" requirements (such as they are, there is no Resistance to counter). In effect only the deployable forces are in game. The Germans have the Resistance to consider, and France has no 'safe zones' in which garrisons could be said to be, and hence removed from the OOB. The Axis has to have the option to put security troops into the front line, and there needs to be penalties for doing so (both for balance as a game, and reality as a simulation).
If you want a problematic Allied force, it is Coastal Command, which can be denuded, and even the NI only units sent to the Med (unit it makes no difference, after mid 44). There is no problem with letting sea control default to the Axis until you want to invade France. Either that force shouldn't be present (until needed for invasion cover - but that is a problem from May 1944 on, as the Allies could mount invasions any time after the weather improves, or before for that matter), or there should be some competing thing that the force needs to do (with penalties) Some of it is interdicting ore shipments and coastal shipping in Norway, and most is hunting Uboats in RL. I haven't studied how much the Axis would benefit from coastal shipping in NW Europe once the rail net is severely damaged but interdicting this isn't enough to occupy all those 4 E patrol A/c...
I have a cunning plan, My Lord