I know this discussion has come up in the SH3 forums. Keyboard U-Boat captains who want to claim that sinking that one vital shipment of Sherman tanks cost the Allies the battle in Normandy and therefore they single-handedly won World War 2 for Germany.
Japan's shipping is a lot more fragile than the Allies, but to really gauge what effect you have on the war you would almost have to have some vast sub-routine running the entire Pacific War...for both sides. After all you have to calculate the effect of not just the ships you have sunk, but what those 100 odd other US and Allied subs are doing too. Not mention the surface ships, planes, Marine brigades, etc on your side as well. For example, if you sink the
Shokaku prior to the Port Moresby operation does that mean the Coral Sea battle is called off and so is Midway? Are the carriers marked for the Midway operation directed to the South Pacific instead? Does it logically amend the war to take in effect what you and other factors cause?