I used the frontage table from the Wiki with the latest patch for my analysis.
Let's say that you have one Division in a Corps with the usual 4 batteries of artillery, although the artillery can be any number. In combat, this Division's elements all fire at one target. If the target routs or is destroyed by the first firing elements, then the other elements' fire is "wasted".
Now we have the same Corps with one Division, however all of the artillery is at Corps level and none are in the Division. In combat this Division's elements all fire at one target, but the Corps artillery fires at a second "strongest" target. You achieve a one-two punch with the same number of elements.
So one could have both artillery in the Divisions and the Corps. That's where the frontage comes to bear. If the total number of the Divisions' artillery is the same as the frontage for support elements, then the batteries will fire at its Division's target and the Corps artillery won't be employed at all. The one-two punch is lost. As you can see from the frontage table, it only takes 8 guns or less for the artillery to reach this number in all but the open terrain type (clear/prairie/desert/wood).
From this analysis, I always use Divisions with no artillery in a Corps. My Division has a sharpshooter, maybe a Marine/Sailor for river crossing, a couple cavalry elements and the rest infantry. I put two of these divisions in a Corps which usually leaves eight or more slots for artillery. Thus, I always get the one-two punch. The Corps with at least two Divisions also has a total of 4 Divisional cavalry elements for the screening bonus to the hide number.
I build 20 pounder artillery, which is the biggest you can attach to a stack without a loss in mobility. I'm not stuck buying a bunch of brigades with only 6 or 12 pounders, but have real, long range, ground pounders. My Divisions also have the benefit of over 20% more melee types who can fix bayonets at range zero, where Division artillery stops firing. As you can see from the frontage table, most often 8 or less support elements are used, so at least some of the Corps guns go hot. In open terrain, I just employ two or more Corps, especially if they follow Napoleon's advice (MTG). I don't have to fuss with building "perfect" Divisions, because if you don't buy brigades with artillery, then you don't build Divisions with artillery from them.
However, if I want to guard a mountain pass or city/fort, then I do use Divisions with intrinsic artillery to save on Command Points. So a Mountain Division usually has a sharpshooter, eight infantry and three batteries (from the frontage table). A garrison Division has the same plus five militia. At least a size 2 city can hold twenty elements without crowding, so this Division is perfect for garrison duty. I can still rail in a Corps commander with some extra artillery to a threatened city if required.
Your comments are welcome.