Habitual association versus modularity
I'm sure no one doubts that there are advantages to each. At what level do we draw the line?
When I was active, brigades and above were considered modular. Battalions and below were really permanent teams, to the extent that a battalion commander would often get the same attachments each time a battalion combat team was formed.
Should this level change? Upward or downward?
Also, should we skip levels between habitual association at lower levels? For example: permanent platoons with permanent fire teams, but with the teams to be mixed and matched into modular squads? Or, permanent companies with permanent squads, but with the squads to be mixed and matched into modular platoons?
You get the picture. Where's the proper balance?
What's the benefit and why?
I think the Australians have it about right, with permanently formed battle group HQs able to command 4-6 sub units as and when required. - so you just bolt on the Companies, Squadrons and Batteries as required. This is also pretty much the way the UK is going.
This is why I think sub unit doctrine is so critical and so under studied.
I do like the idea of near permanently formed Brigades as that's where you'd get your cap badge/tradition/culture from. - so a Brigade would be 4 Battle Group HQs, and then 16 Sub units.
IMO, currently a lot of sub-unit roles and TOE's do not make a whole lot of sense, bearing in mind the current progression of weapons and sensors, but that's another issue.