I have to agree.
In my current game with Nix, he left 1 INF in Alaska, nothign in Western or Central US, and Western Canada was vacant.
I slipped 1 of my 4 TRN, along with a BB up to SZ63 and dropped 2 INF into WCan.
Sure, I only gained a buck, but I could have walked into both Central and Western US if he had not moved existing Eastern forces to Central and built forces in Western. And with the BB, he had to build more than just 2 INF in Western to block.
2 INF from Eastern are 2 INF that will not land in Europe in 2 rounds.
And those 4 units built in Western are 3-4 rounds away from Europe.
I bailed on the next Japan move and sent those 2 INF back to Bury for the march to Moscow.
My losses: 1 turn of movement in Asia on 2 INF.
US losses: 2 round delay on 2 INF, 3 round delay on 2 ARM, 4 round delay on 2 INF reaching Europe.
And of course Japan collected an extra IPC when they took it, and will collect a second one before the US takes it back since the UK did not do so :-)