Every military is organised differently. Thats the 1st thing you have to realise. There is no "standard" only in the broadest sense. Strategic situation, manpower, geography, tradition, political system, economy all play a role in how armies (and navys and air forces) are structured.
Take a look at the various WW2 combatants to see how they started the war, and how they evolved, some for the better, others for the worse, but all differently.
As for the Soviets, they learned the hard way about combined arms strategy, just as the Allies did. The Red Army of 1944 was not the Red Army of 1941. Just as the Allied armies in 1944 were not what they were in 1940, or 1942.
