Well, yeah, a lot depends on the playing caliber of your opponents. If your Russian player doesn’t work his defense well, then Germany will probably push through and grab Moscow faster than they normally would. If your England player doesn’t properly protect London, like maybe putting too much in the Med against the Italians or even trying to rebuild the fleet instead of troops/planes for London’s defense, Sealion could happen for Germany way easier than it should.
Basically, I am referring to games between players of somewhat equal experience/talent. If the Pacific Allies can manage to keep Calcutta out of Japanese hands and the US spends wisely in the Pacific, mainly warship and aircraft purchases, then Japan could possibly be cornered on their island by round 6-8 or so. UK India has to defend Calcutta as much as possible because once Japan gets it, it is unlikely to be liberated. However, once UK successfully defends Calcutta against a Japanese invasion, then it is more likely that the threat will be over and Japan will start getting pushed back. Any Japanese forces in the area will simply be too weak to make another attempt, and they will probably be VERY short on land units anyway.
Then, with the powerful US Navy coming into the scene, Japan will start losing ships that it can’t easily replace. Meanwhile the USA CAN replace it’s naval losses much easier. China and UK will start making headway on the mainland, driving Japan further and further back to the coast. ANZAC will be hitting any smaller targets. Before long, most of the Japanese navy will be depleted and the US will have a large fleet right in SZ 6 convoy raiding Japan into the poorhouse.
Also, I wouldn’t bother getting too many transports, men and tanks/art for USA. Let ANZAC take all the islands from Japan and the Brits and Chinese (and maybe even Russians) take the mainland territories. USA’s job is to kill that Jap Navy then surround Japan. If UK and Russia are done right, Germany/Italy won’t yet have their needed VCs and the US can start sending troops to Europe in a big way. Once US gets a large force in Europe, or better yet takes Rome, Germany will be doomed.