Well, I scanned the forums and did a search, and it seems my question has not yet been asked (or at least I'm unable to find it)...so.....
Looking at the division designer window from the dev diary, it "appears" that a division has a maximum amount of combat or combat support bns of 16 (5-4-4-2-1).
Is that indeed the max?
Looking at a US infantry division late in the war,
3 combat commands, each of 3 infantry bn's
1 artillery brigade (regt) of 4 arty bns
1 engr bn
1 recon bn
that's 15....which fits....
but what about the following:
AT bn (or Tank Destroyer for Mot/Mech/Arm divisions)
AAA Bn (mostly disbanded late in the war because Germany lost control of the airspace above the battlefield....for the most part)
(I'm not going to include "Tank Bn" because I don't think that the game mechanics allow it in an leg infantry division, but some including 1st Infantry division had one)
so...that's 17 (not including the Tank Bn)
Other nationalities had different doctrines/formulas for creating the "best" division, but I'm not conversant on them. I THINK that the Brit's had more bn's in their divisions. I'm pretty sure that the Soviets did.
The question really is I guess, is that display static? or does it evolve into a 5x5 matix (not including the support company column) as "experience" or doctrine or something creates the ability to build bigger divisions? Do currently "locked" cells, when opened, modify the template to show another locked cell below?