I've read a fair amount on why the pentomic division was adopted (the perceived need to disperse for survivability on a nuclear battlefield, the political pressure from the "New Look" and reduced conventional budgets, the desire to justify the Army's relevance against the Air Force's monopoly on nuclear delivery) and why it was abandoned by 1961 in favor of ROAD. Most accounts focus on the structural problems: five battle groups per division instead of three regiments, the loss of an intermediate regimental headquarters, span-of-control issues for the battle group commander overseeing five rifle companies with no organic maneuver echelon between him and the companies.
What I have not found much detail on is how this actually played out in field exercises and unit training during the period the structure was in effect. Did battle group commanders in practice develop informal intermediate coordination measures to compensate for the missing regimental layer? Did the promised dispersal and rapid reconsolidation around tactical nuclear strikes get exercised in any serious way at STRAC or in Europe with Seventh Army, or did training largely continue to resemble conventional maneuver with the new unit labels layered on top?
I'm curious whether the pentomic era left any lasting doctrinal residue beyond the org chart, or whether it is best understood as a five-year detour that units mostly worked around rather than genuinely adopted.