@General_D.Fox:
So for Japan, if they are going to assault Moscow, would it be better to have some art along with the stack of inf and arm? Or should I just have enough inf to screen my large stack of tanks?
All the calculations we have done up to this point have ignored the questions about whether IPC, Factory Space, or Transport Space is the choke point in getting combat power to your front line.
Are you IPC limited or Factory Space limited?
If the limitation on production is a maximum number of units, ARM is a good deal and it adds mobility.
If the limitation on production is IPC, ART and INF in ~ 2/3 ratio is great bang for the buck.
If sea transportation is the choke point for you, your ratio is pretty much locked at 50% INF so if you can afford it ARM is the way to put some punch on the battlefield.
There are no easy solutions. If there were, it would not be as much fun as it is. 8-)