I used to shun the J1 Complex, but I’ve since changed my outlook. I still prefer a 4 tran buy (2 IPC from bid of course), but the complex offers it’s own charm.
The allies generally stall the Japanese with the starting units in Asia, or even pull some back to go after the Germans. My mission with the Japanese is to break the allied lines as fast as possible, earning maximum cash from the Russians. Japan has an entire airforce to do this with, and can generally use the two battleships for the purchase as well.
Of the three routes across Asia the North is the quickest, and takes Russian income. It requires defense of Novo by the Russians.
The Chinese route is more difficult (an extra territory to Novo), setting you back minimum one round. Defence for Russians is again Novo, but you may get the chance to trade Kaz as a bonus.
Indian route is the longest, and offers no assault on Russian income. It is the easiest to protect with minimal force (Bombards) provided you keep fleet in the area. Russian defence is from Cauc, where they’ll likely be anyway (German threat). It is also the easiest for the allies to provide support against.
You’re going to build a complex regardless by J3, and by placing on J1 you are locking in part of your strategy quite early. Indian route gains more long game reward (near shuttle to Africa) that will aid a match you are trying to win by outproducing the opponent (pulling in more IPC). It puts the least pressure on the allies in early game.
I’ll finally get to the point. Placing the IC J1 with a 2 Tra build allows you to place 2 or 3 extra arm on the mainland J2, meaning they can reach Sink J3 from any starting territory, and Yakut if you place in Manchuria. This gives you maximum power for your J3 assault to break whichever stack you wish, not just the attack power of the tank, but the necessary fodder to allow you to bring your air support for the kills you seek. 3 or 4 Armor is significant. The best you can do with a 3 Tra 1 Arm build is 2 Arm, and the 4 Tra build offers only your starting unit.
Is committing to a complex placement J1 worth it for the one-time bonus deadzoning/attack/suicide J3? I believe it is if you plan to push 11 units across either Yakut or China to Russia as fast as you can. If you plan to take the Indian route, I’d say probably not.