Let’s look at Europe for a moment…
USSR pickets a 3 territory wide front: Archangel, West Russia, and Ukraine at a cost of 9 IPC’s of units (3 INF).
To have good odds of securing victory in all 3 territories, Germany needs to use 2 INF and 1 FIG in each. So Germany has to devote $48 IPC of resources to reclaim those 3 territories from $9 IPC of Russian units… 3 territories Russia has already been paid for. If Russia hits just ONE German defender, the economic trade is already in Russia’s favor just from value of units lost and value of territory Russia was paid for.
But the main thing is that, especially in the earlier parts of the game, Germany is INF starved on the Russian Front. 6 INF represents pretty much ALL of the INF left on the Russian Front after R2. And 3 FIGs represents more than half of Germany’s FIGs. So no massed attack on Naval fleets with AF while those FIGs are engaged in ground attacks in central Europe.
And Germany is not likely to push forward with their tanks due to lack of INF screen, since their INF is spread over 3 territories. If Germany DOES advance ARM with slim INF shielding, Russia counter-attacks, or strafes, losing INF while Germany loses ARM, then Russia pulls back preserving their ARM and FIGs. And if Germany pushes back in only 1 territory, that is extra free revenue for Russia the next round.