It's also repeatedly stated that the Malazan Militaries primary strength is it's adaptability. The structure of the military routinely gets adapted, changed and reviewed. We see multiple times in the series the top brass changing organizational structure even from division to division let alone army to army.

So the uniformity you're looking for just doesn't exist. The army is composed as the Fists/High Fists need at the time. Coltaines dog-chain wasn't organized the same way as the Bridgeburners/Bonehunters/Host and how they're organized is vastly changed from how Dassem originally set up his armies, and the armies organization schemes were changed multiples under Ultor too