A sub heavy fleet is not a valid counter to the Japanese navy, because they can always match you sub for sub with superior income. There is no match for the heavy bomber. Eventually heavy bombers will win out in the sea, while the same cannot be said about subs.
Also, even if you somehow overpower the Japanese with subs, then what? What are your subs going to do on land? I don’t feel that a sub heavy strategy is a good one (maybe in AARE it’s good because of convoy raiding :lol: ). The Japanese can always run away before your subs hit and then you’re left with 100 IPCs of subs with nothing to do on land. But heavy bombers can also make a huge wreck on land after they’re done cleaning the sea.
Also, I feel the tank example is invalid, because tanks do not roll 2 at 4. They only roll 1 at 3. That makes a huge difference. There is no infantry unit either in terms of navy, there is no unit that defends at a 2 and is cheap. The “best” thing you can come up with is a destroyer for 12 IPCs that rolls at a 3 against air.
Economically on land infantry will counter tanks. 30 IPCs of infantry on defense beats 30 IPCs of tanks on offense. However, on sea this no longer holds true. There is nothing that beats heavy bombers IPC for IPC on defense. 1 hb beats 1 destroyer, 1 hb beats 2 transports, there is nothing you can do if you have equal income to defend against heavy bombers except delay for a while. I don’t see why this is so hard to see.
All that you’re talking about is that you have to overcome the initial inertia of the existing Japanese fleet + investments, but that is true of any anti-navy strategy, you have to overcome a huge bump. I simply think that heavy bombers can easily overcome this bump, even you said yourself it takes 5 times to build up the necessary bombers, while navy heavy takes at least 3 rounds more to become threatening.
As I’ve said before, in practicality, buying all HBs to take out the IJN wouldn’t really be a game winning move, IMHO: too costly as well as easy to stop (as you so aptly point out)… it’s not like Japan wouldn’t see it coming either.
And as I’ve said before, I don’t think it’s a game winning move either, but certainly nothing else would work better should one decide to go KJF. Sub heavy or navy heavy is much slower and also the Japanese CAN match you defensively with their income, but with heavy bombers eventually they’ll have to give up or roll for their own heavy bombers to keep the seas clean of all ships.