America is building and not advancing because if they advance they have a significant naval threat to contend with that could eliminate them in short order.
Remember, Japan has 9 Fighters in their starting set up! With 6 Fighters on Carriers and 3 Fighters along the coast, it is theoretically possible to hit the Solomon’s Sea Zone with Cruiser, Battleship, Destroyer and 9 Fighters.
America can get, at most, 2 Destroyers, Carrier, 2 Fighters, Battleship in Solomons by the end of US 1.
That’s a 99% in favor of Japan battle, by the calculator.
Now, if America buys, say, 5 or 6 submarines in SZ 56 and consolidates there, why wouldn’t Japan buy 3 Fighters and some ground units? (This would give them 12 fighters that can hit your navy; 6 on carriers that land on ground territories and 6 from ground territories that can land on carriers.)
And if America continues, Japan only needs +2 Destroyers to effectively end the Submarine threat from any one or two territories on the board.
With 12 Fighters, 3 Carriers, 3 Destroyers, Cruiser, Battleship (+46 IPC) the Japanese are effectively ensconced in protection for a while and still able to give America enough pause that they keep a wide berth between them.
And once Japan gets 2 or 3 ICs running on the mainland, they don’t need to control SZ 62 any longer and can move their fleet away.
Do not get me wrong. I am not saying America cannot defeat the Japanese in the Pacific. I have plans that I think work effectively at dismantling the Japanese fleet. But submarines are not the mainland idea behind it.
I believe America needs to focus on Destroyers, another carrier (to land those fighters on), bombers for long range punch and battleships. Honestly, in this scenario, Cruisers are not cost effective. Just my opinion on that. Cruisers are great for the Atlantic, they give you bombardments and can be added to the British fleet at minimal costs to protect against the Luftwaffe. (Carrier, 2 Fighters, 3 Transports and just enough cruisers to stop Germany from posing a serious threat to the fleet is my aim.)
As for submarines, those are units I add in two rounds before I think I’ll engage the enemy. Why two rounds? 1 Round to move them into position, one round to make the combat move. By the time i think of serious submarine commitment, the enemy fleet should already be dead, I’m just adding some units for the coup de gras and insurance.
After you control the Pacific, it’s a good idea to put a serious investment of submarines in the water since you can set up a scenario where you can sink anything the enemy builds and have units immune from enemy attack.