Actually, I usually will buy a MINOR IC for Germany and put it in Norway. Sometimes I will put a MINOR IC in Romania too, but it depends on how the forces are down there. I find that the Major IC in Berlin is usually sufficient to supply both the southern drive and the eastern drive into Russia. I need some tanks and mechs up north. Usually that is the force that takes Leningrad along with air power and unless I have an IC up there, I have always found it hard to supply those troops, especially if UK is still in the game because they are harrassing my navy too much.
I do this as well. Even if you don’t want to spend big money up there for an assault force, 3 inf a turn is cheap and VERY helpful. Germany needs Norway for an NO, and find that once you lose Norway, getting back is very annoying. A minor IC and 3 inf a turn means that Norway is substantially defended, and that UK or Russian will need a dedicated push if they want to take it.