Now we’re talking about either attacking with the Russians OR attacking the Russians as Japan on game start?
OK.
I disagree here. If Japan wastes a lot of resources killing the Amur stack, that’s just it, a waste. You’re just building up a future unit deficit against China and India by not consolidating your forces in the right places. It’s also worse to piddle around against the Chinese and the UK at game start since both powers can make MORE money as the game progresses compared to Russia which will always stay close to a static 37 IPCs (at least for the first 3-4 turns).
True, you could argue that those troops aren’t doing anything anyways, but what would you rather have on J5: 20+ land units you carefully marched across China to Burma with loaded transports in range of India; or 5-10 land units possibly without support isolated in Russia somewhere?
Same could be said of Russia with its 18 INF in Amur, if Germany goes hard for Barbarossa with a G2 build and attacks, you’ll be glad you were cautious with them at game start around R6-7.
Even though these land units aren’t effectively “used” every turn, they still have “threaten potential” to influence future events and builds across the board.