Fair suggestion, going to the regs...I don't have them for the cavalry, though I've read much of the infantry. And it is true, compared with the British infantry regs, the French go MUCH farther in the 1791 Rules and Regulations into writing up elements of usage above the battalion/regiment. But, as I mentioned, there is not much in English (at least that I've encountered or been able to locate) about how any of the participants employed those rules and regs at the level between the battalions/regiments and divisions or corps.
Napoleon's removal of cavalry from divisions strikes me, on one level, as a return to prior practice which, during the Seven Years War and still retained to some degree in principles into our period, placed cavalry masses on the flanks under commanders different from those in charge of the infantry of the line of battle. Certainly in both periods cavalry gets attached to infantry, or infantry to cavalry, to fulfill special tasks, but during the Seven Years War, the cavalry generally seems to operate pretty separately from the infantry...to the point in which thinkers like Fritz are lamenting the failure of the captains in each branch to adequately understand the operations of the other.
With respect to Belliard's longevity as chief of staff for the cavalry, you may have put your finger on a very good point: long-term operations TOGETHER would inevitably lead to development of SOPs and customs of cooperation and collaboration that would transcend the rules and regs. Then what is hard for moderns looking back, is how rarely such things were written down or preserved, making it hard to resurrect.
While tactics are, of course, a product of experience, as you say, there needed to be a concommitant command structure networked together in such a way as to promote or faciliate the evolution of those tactical or grand-tactical usages. Very little light is generally shed on what those structures were and how they operated in the hierarchy between battalion/regiment and division/corps.
And while leadership and training are naturally key in so many walks of life, it is interesting to see the extent to which Frederick the Great is writing, philosphizing, and collating his thoughts about tactics and operations to his generals, in order to nurture their capacities and nurture the equivalent of doctrine, while I am not aware of Napoleon sharing such leadership development with HIS lieutenants to nearly the same extent...but perhaps I've missed those books? And, yet even Fritz doesn't dwell much between the handling of battalions and squadrons and of army wings or entire armies. The word "brigade," for instance, rarely appears. Was there some other echolon or command grouping?! Certainly the Napoleonic brigade, division, and corps structure provided a pretty overt framework within which to work, compared to the command structures of the Seven Years War, but the actual battle-handling process, the application of battlefield leadership to leading, doesn't get very much attention above the tactical level and below the operational.
I am gradually coming to see this relationship as a sandwich, a nice slice of tactics and a nice slice of operations, but I am waiting for the goodies in between to show up in military history and historical appreciation: the ham, the cheese, the lettuce, tomato, mayonaise, all that good stuff. There's some increasingly reat bread out there, but I find myself missing out on what oughta be in between :o)
Cheers - Howie