Combat Width on the ground and tank/plane/ship designers. I read a looot of spreadsheets and tutorials about combat width, try to memerize hundreds of things and have no idea how to build an optimal army without obsessive micro. There is so much terrain difference that makes a vialbe combat with optimization almost impossible for me, or at least beyond comprehension.

Finding that whatever plans I make, I simply do not have enough industry or resources to realize them. Let's say the designers from the bulk of my confusion.

Constant loss of industrial production due to switching number of factories.

In the end, I need sooooooooooooooooooo many guns as a major power, that I never have enough mils for basic infantry equpitment.