We have the original Daniel vs Johan Germany vs UK streams for that. Daniel spammed infantry for the entire thing and won.
Hearts of Iron III was not per se a bad game, but the OOB was the most bad feature for me.
For example if you would like to play russia, there were so many divisions without an general/commander and after the great purge there were even more and new generals could only automatically be attached to new divisions, but not to old. It was just a mess.
It was not possible to make quick game with russia, only because of the oob, there were always that annoying half hour up until 60 minutes, where you had to assigne some generals. OOB is for me really a feature like " Super nice idea ! " but it dont work.
I hope I will never see it again, never ever.
I got around that by doing it once for whatever country, then running the game for one hour of game time, then saving with the name RUSSIA_START or GERMANY_START or whatever. Made the future games much more enjoyable at the start.
As far as HOI4 goes, while not going to the division level, I can see at least doing an OOB with the existing levels - Field Marshals and Generals. Seems silly that to use the specific skills of the generals to take certain points along the path of the overall offensive, we have to separate them out from the offensive or lose those bonuses.
Would love to see a situation where you could have several generals under a FM, and draw overall plans for the entire group, but also within that, be able to draw the more specific plans for the General, which would then revert to the FM overall plans when their specific task is done and they join in for that.
Yes, you can do this by simply microing for some of the units, but A) they aren't getting the general's bonus - and B - if you have them under a general, they'll just take the objective and stop, unless you wind up coordinating with the rest of the FM's units.