Germany’s problem is landing zones for the fighters. The British only need to protect SZ 109 so they can drive a destroyer to SZ 125 and sink any submarines. On top of that, they have 6 fighters to scramble to protect the fleet. That’s 24 Punch for Fighters requiring 8 Attacking Fighters just to match it. Add to it any surface fleet and defending carrier bound fighters and you’ve out matched the Germans pound for deutsch mark.
If that wasnt bad, in order to hit SZ 109 they need either W. France or Holland to land on. Usually that’s not a problem, but towards the beginning and end of the game, it can be an issue to contend with. Not to mention once you land there, you have no pre-existing airbase to extend your range or scramble with, nor do you protect SZ 112/SZ 113 against British attack.
For instance, Germany has 2 Strategics, 5 Tacticals, 13 Fighters and no kriegsmarine (since they rarely do anymore). To counter this Britian has 6 Scrambled Fighters, 4 Carrier Fighters, 2 Carriers, 1 Battleship, 1 Cruiser, 3 Submarines and 5 Destroyers (a moderate fleet.) Assuming Germany has a place to land, they only have a 15% chance to win.
England had to invest to get the fighters and had to move the carrier into position to cut costs, but since they were sending fighters to Russia like mad to prevent it from falling, they have the fighters to move back. To clear SZ 125, they send 10 Fighters, 1 Destroyer and pretty much anything Germany might have gotten there, is gone. So they might be costing Russia 5 IPC, but are losing 6 IPC in submarines to do so. A losing battle for Germany. (And iwth only a 17% chance to kill the destroyer, they might lose something attacking SZ 125 to reclose the shipping lanes.)
America has a larger fleet, mainly because they have to protect SZ 91 and SZ 95 to perform their landings. Figure about double what England has, if not 2.5 times what England has. We’re talking 11 rounds remember, so America has earned about 800 IPC give or take a few dozen IPC.