In most games there comes a point where it really isn’t possible for Germany to defend the 4 core territories and still maintain pressure on Moscow.
There is just too many spots for the Allies to land, so before losing a bulk of your troops defend or keeping valuable inf needed against Russia shift everything East and get them involved.
Correct, you want to trade with ftrs and inf. Most games you should have 4-5 ftrs and 1 bom. Which gives you a good enough punch to repel most first landings by the Allies. If UK lands 2 inf, attack with 3 inf, 4-5 planes and repeat while defending Ger. You can do the same with SE, but there it might be nice to use Inf and Arm and alternate. One turn you take heavy protecting the arm from counter, then you vacate on the next German turn.
Now if the Allies DO land heavy in WE, you can attack with your inf, ftrs AND arm and then retreat back to Ger after you strafe the heck out of them. As long as you kill 4 more units that you lost you’ll be fine since that essentially covers the loss of WE for that turn.
Example, you have 10 inf in WE, 10 in Ger, 4 in SE and 10 in EE with 6 armor. Move the 10 inf in Ger to EE, 10 inf in WE to Ger, 4 inf to Ger from SE and place your 8-10 units in Ger. Now look at what the Allies see, Germany stacked with about 20 inf, 5 planes, EE with about 15-20 inf, 6 arm. Now even if UK dumps 8 units to WE and US follows with 10 units, you easily have 30 units (inf+arm+ftrs) to smash him with, yet you still have a good force to threaten Kar and Ukr. In this case the UK will probably drop 2 inf to WE (to claim the 6 ipc) and the rest to either Nor or Kar. That is an easy trade for Ger (3 inf, 4 ftrs) and still allows you to threaten Ukr and move inf East. As long as you keep about 15+ inf in Ger and your armor safely protected in EE you can keep WE lightly defended (1-2 inf). I leave it empty at first if UK has its BB.
If US can land in SE, then instead of shifting 10 inf to EE from Ger, shift 6 and drop 4 to Balk. This allows you to bring 15+ inf and arm to SE to counter a US move and should protect against a counter on the next US turn.
As for the AA guns, shift them as well. 1 to EE from Ger and 1 to Ger from WE. Or if you have to vacate EE, then stack Balk with your troops and an AA.
I find I usually have to deadzone WE by about G4-5, unless I’m doing really well in Afr or something.