I actually agree with most of what you say including the fact that I think Japan holds the edge, particularly amongst inexperienced players. I dont see any way for the game to take 20-25 turns between experienced players (unless maaaaybe fighting out to the bitter end when the game has long since been ‘over’). And yes, if you have the DEI and have taken out the Brits and Chinese and the US isnt in position to take the DEI back THAT turn, the game is over IMO.
Also, FWIW, I’m the person advocating what LOOK to be bad moves individually, but taken together add up to good moves the Allies as whole. Unfortunately it’s tough to articulate specifics since it’s going to be different from game to game. But in general, what I mean is that you can leave a few ships exposed here and there or make a few invasions or leave a few planes exposed in places etc because in all likelihood SOME (or most depending) of them will survive and annoy the Japanese or else the Japanese are spreading out thinner to take care of all of the threats. This in turn leaves Japan open to counter-attacks, or losing battles, or even simply risking higher casualties by not having massive overkill.
For example, suppose it’s the Brit turn and they have a few ships and a TR and a few planes. They can send those ships and TR to snipe off a stray Japanese ship (a blocker usually) and still send the TR to land somewhere in the DEI or behind the Japanese in Asia etc. They can send the plane(s) to reinforce Malaya or a previously held island etc (or somewhere you know the Japanese want, but need TRs to get to). Looking at it solely from the BRIT view, these are ALL ‘bad moves’ since they can easily be countered by Japan. But then it’s the ANZAC turn. And they can move a sub into a sea zone to raid 2 IPCs and they can move a DD and a TR to a different island and they can move another TR and DD into position to be able to hit the PI or another DEI zone the following turn. They also might have a plane or two to throw on the Brit island they just took. Again, in isolation, these are all ‘bad moves’. The Japanese can take any of them out fairly easily. But now it is the US turn. The US moves a fleet down to Australia and has another one moved to Pearl, and has a few ships already in Australia that can reach another island of the DEI (or FIC). They can again move and take an island or reinforce one. Or they can take one of Japan’s starting outposts. Or maybe they can put some planes on Wake (if the Japanese havent had time to occupy yet). Once again, to solely the US player, these all look like more ‘bad moves’.
Now turn the table around and look from Japan’s view. One or two of the DEI are re-occupied (one possibly with a plane or two). The US is at Wake, is threatening to invade the DEI again next turn or converge and hit Truk, the ANZACS have a sub and DD in irritating places and the Brits have made a hardpoint at Malaya (or wherever) that will take more than just a single TR + some aircover to smack down. That is a lot of dispersed threats to have to deal with and Japan will likely not have the capacity to kill them all without leaving themselves vulnerable the NEXT turn (which starts the cycle again). Japan has a lot of ground to cover and not a lot of TR and ground troops to do it. Sure they can build both, but they will eventually run out of naval assets in sufficient quantity to cover all the vital areas. This is made worse because any BB or CV that takes damage has to retire for a turn to heal. Also, if the Japanese are moving assets into the DEI and as blockers to prevent the next turn’s annoyance, they are limiting their mobility to respond to future threats by not being at a friendly naval base. This opens up areas at the fringes where Japan can’t effectively respond to the next wave of threats. Usually the Brits are good for only 1-2 turns of this unless they manage to hold onto some income (unlikely IME). But by that point the US and ANZACs can often pick up the slack.
Obviously all of the above is not going to be possible every game. But the theory is always the same - give Japan more threats to deal with than she has assets. This leaves two basic choices: respond en masse to a few of them and suffer the consequences of the others or spread out to deal with multiple threats but be in a weaker position to respond to future moves as well as being more vulnerable to damage in each battle and to enemy counter-attacks. Will it work every game? Of course not. If it did, it would be an imbalanced game in favor of the Allies. But I think the above provides a workable foundation for Allied strategy.
My sense of it that each succeeding edition of A&A since the original has been designed to push the players to play more ‘historically’ than prior versions. And without hard and fast rules to demand such, the designer(s) have used geography and economic goals to encourage it. In this case, the zone connections CLEARLY encourage the Allies to fight across the southern part of the map (as they historically did). And this in turn encourages Japan to expand south to meet or pre-empt that threat (again, which is what she historically attempted). That is not to say to that there are not other alternatives, but the ‘push’ to have the players fight in the South Pacific is pretty clear. So IMO it makes sense to use the historical Allied strategy of early raids followed by a steady march across the South Pacific as a starting point for their early moves.