Keep in mind that for a long interval of the war, for many of the "types" of British armoured/tank regiments, 2 of the tanks in a squadron HQ were "close support" - armed with something that threw a heavier weight of HE. With modern battle tanks, that's not needed.
Firefly Shermans were in short supply, so 1 per troop was allocated. Sometimes used that way; sometimes consolidated into single troops. [Add: and the employment of brigades in divisions - Sherman, Cromwell - was different than the independents - Churchills - still influenced by early war "cruiser" / "infantry" bias.]
Looking at all the fudging around they did and poor results in many cases, if I were designing an armoured force I wouldn't start with the British as my template.
Done rationally, you'd start with a "literature survey" : pick some nations (eg. Germany, US, USSR, UK, France), and pay historians (one or two per country) to do a deep dive on the evolution of each nation's armoured forces (troop to division) from immediately pre-WWII until now, and report back in 6 months. Find all the points at which any kinds of organizational changes were introduced (from troop to division) and identify the reasons. Would include surveying all the published doctrine, SOPs, and AARs. Winnow out the ones decided by experience in battle and focus on those (ie. ignore budget cutbacks, equipment shortfalls, tradition, wild hair up the senior black hat's ass, etc ).
Then come up with some proposed designs, try them out with a hockey sock of map/estimate exercises, and proceed with the best candidates to force-on-force trials.