anyway back to the topic.
personally, I prefer to buy primarily inf in global. Unlike revised and aa50 where tank purchases and counter attacking were common place, armor units cost 6, making infantry better attack units than tanks (due to cannon fodder factor). I buy artillery if I forsee myself attacking. I don’t like doing multiple battles, because germany has all the air. I buy mech/tanks if I need to utilize their movement to attack the next round.
Still one solid stack is better than two mid sized stacks. imagine you have 40 inf. you split 20 and 20. one 20 size stack dies to a 40 size stack from germany and you inflict maybe 10 casualties, now germany has a 30 size stack left.
That is the reason why you see the super stacks.
Another reason you see the super stack, usually at bryansk is because there is an impassable terrain seperating north and south german stacks. So germany has to super stack up south or north next to you before causing you to retreat. If he moves a mid size stack, you all in or strafe it (hit it and retreat).
The slugfest works in your favor as it takes time for germany to move up to you. Usually everything germany has to attack russia has already been bought at the end of G5, with the exception of ukraine and novgorod armor units and bombers from west germany/germany.
Every single unit is critical for the showdown at russia.