But in reality, you don't have to wait months for supplies to "catch up" in that way. They follow the troops. America doesn't start supplying its Operation Torch landing force by sending ships from Washington the day they land in Africa; preparations are made for supplying the troops at sea, immediately after landing and then during transition to a regular system. Hearts of Iron 3 ignored this altogether, Hearts of Iron 4 abstracts it into connectivity without delay. (The system doesn't really model supplies, but rather connectivity to a supply network.) Ultimately the goal in HOI3 was to be sufficiently connected to the supply network, which HOI4 wholly retains. It just does away with waiting for arbitrary and unrealistic supply flow--this would be a different discussion of the HOI3 system had any semblance to real supply flow, including use of supply dumps, etc.