In a real army or the phantom Canadian army in someone's feeble mind.
On a thumbnail I believe in small divisions (10-12,000) or so. Others look at 15,000 to 18,000. But that's if your talking something intended to be deployed as an entity.
So to thumbnail it again, a corps would have two or more divisions plus corps troops so around 25,000 to 45,000 troops.
I'm having troubles conceiving of what's in their heads - my guess is its more in the nature of Milareas and Mildistricts than corps or divs. I could see a district being able to handle around 5,000 so in (around 7 battalions of 700 each) which gives you around 20 districts in lets say 6 areas.