In this game:
https://www.warzone.com/MultiPlayer?GameID=15908792you can see me and a friend making a race who can beat their AI faster. On my side you can see that im doing what i just said. keeping a low border against the AI while keep expanding. even when i break the AI bonus i only attack it with very few units to due me knowing it wont properly defend anyway. while on the other side you can see my friend that isnt that experienced against fighting AI's and makes a ton more high stacks. that leading to poor expanding and while he still wins against the AI im just a ton faster than he is and a lot more efficient. even with keeping a low border while he has a high stack border i have almost the entire game more inc than he does while my AI has less inc than his AI has.