You have a valid point. Germany must be prepared. If Hitler builds nine transports and moves the troops west for sealion do not attack Russia. However if the motherland just spent fifty of its sixty round two dollars on a dozen infantry and some mechs then Germany is in better shape. Still like you say, Germany has to watch out for them Russian kill zones.
IMO letting turns pass and letting America build fifty ipc of units a round is a negative trade for that five ipc national objective. The game like chess has an odd cadence or iniative factor. The axis only have so long before the allies are prepared.
To be overly extreme.“America on round one is a helpless baby. Give her five turns and she is ready to flex”.
In chess them five turns are free moves for your pawns towards the other side of the board. In the game them five turns are territories closer to Russian factories, Moscow, or India.
At the very least each territory further into Russia you get is a turn longer it will take them to push you back. Each of them turns they kill your sacrificial one inf while you build out of German factories