Great points, PS, and others.
I don’t J1 as much anymore. J1 is good for the straight to Calcutta plan. Calcutta used to fall every game; now it rarely falls because in order for Japan to hit Calcutta with the necessary “almost everything” you have to leave SZ 6 and Japan vulnerable for 2 or so turns. This is where the KJF 100% USA plan is pretty much de rigeur because its the only chance the allies have to gain position before the Axis gain threshold income (65-70).
The key to keeping Japan alive is keeping a warding force where it can attack the USA if it ‘steps up’ to you. This is about 1 grand fleet on SZ 6 along with a good portion of your bombers and fighters. Only if they are on Japan or Carolines will they be able to strike the bold American Navy stack. If your opponent is a noob or trying to KGF (semi-noob) then Japan can do everything it likes without fear, but, most stronger players will build a huge USA fleet. If it squats on SZ 6, you may not be able to rebuke it if too many ships and planes went elsewhere; either way it prevents you from laying a decent fleet because 10 lays and 70$ is still not enough to push US off your main lanes.
Japan has to intimidate the US, because if Japan is actually forced into confrontation, not all his ships may be able to make it. Even if they can, Japan may “lose for winning” because they are forced to use their one-shot everything all in fleet in a 50/50 odds battle which is then destroyed on the counterattack by US planes, ANZAC, UK etc.
If Japan and USA are both demolished on the water, that’s actually good for the Allies because the USA imm. follows Japan’s turn with a relief fleet (or two!), and ANZAC may still have one, whereas Japan can have “won” every battle but lost the war because its got like 1 BB left, 2 factories to feed, and hasn’t hit threshold yet, and doesn’t control the Pacific or India. Then the USA has the advantage because without Japan being able to ward them off, they just head to SZ 4/Russia and step right up in Japans face turn after turn. If the USA cleanses the North Pacific, at the least they can rescue Russia, then potentially China.
The funny part is to get around this, Japan just waits until J3. The USA player tends to get bored, placing stuff in the Atlantic while he waits to enter the full war. If he sees the Sea Lion or London falls, then he’s pretty much obligated to act on that or lose the game. Any splitting, KGFing, or goofing around will cost the USA the slight advantage in the Pacific fleet to fleet vs Japan, such that all it can do is sulk around the edges of Japan’s new empire.