I’m not overly worried about allied planes in China. If they are in China, they are not attacking Germany or Italy.
However, I do think an amendment is in order, perhaps Japan should attack China on round 1 (to knock down the defenders, you can almost get every Chinese unit on Round 1 if you set it up right) then ignore them from that point on.
IC’s in Sumatra and India can handle the southern front while Japan feeds the northern front. That’s 15 ground units a round (45-75 IPC a round) and remember, China is kinda stuck, they cannot leave China (except to reclaim Hong Kong, big whoop) and they’ll only have infantry to do it with.
Meanwhile, i am not seeing a huge contingent of red army in China because they are focusing on defending Caucasus/Kazakh and Novosibirsk/Urals from Japan while Germany threatens Belarus, East Ukriane, Ukraine and Karelia and Italy threatens Ukraine and Caucasus.
If you choose to wipe out all Chinese defenders on turn 1, then there’s not much resistance from continuing the offensive to control all of China outright.
A northern approach to Moscow is quite time consuming, especially if troops are debarking from Japan. It might also be easier for the US to disrupt this approach, than a route through China or India.
I would only try an ignore China strategy if Germany employs an all out aggressive move toward Moscow. The idea is to try to bring as many troops to bear against Russia as soon as possible. The Axis would probably have one shot for a knock out blow. If that fails, then it’s probably game over since they would be hard pressed to recover mid-game.