I almost never bother to add them, as I find it not worth the hassle of going through them one by one adding them. I just click a couple more times to build more armies.
Interesting idea but how does an Army gain Exp? Moving from planet to planet while you have a second Occupation force once the planet has been conquered? How do they get EXP? By just being on the ground?
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Furthermore I don't want Stellaris to be a warfare simulator or a wargame. This is grand strategy in space, and as such I would not expect to micromanage armies in too deep details. On the military perspective, a unit level is too deep for me already, I'd rather see some more effort on logistic and supply chain instead.
I'd prefer this. I've never played a space 4x where ground troops were a positive influence on my enjoyment of the game.It would be easier to just remove assault armies, let defense armies add Foritifications and flip the planet to "occupied" the moment the foritifcations are 0.