The problem with the economic analysis above is that it ignores the cost required to obtain one of those properties to build on in the first place.
For the US to take Borneo or East Indies (the only 2 islands with 4 IPC values) requires a significant advance investment by the United States JUST to get there.
The FASTEST the US can get to Borneo or EI is US3. And that would only be possible with the initial BB/TRN off Western (assuming Pearl occured). It also assumes that the US did not have to do a Pearl Counter, and that at no time in J2 or J3 did Japan engage the lone BB and TRN sailing from Los Angeles.
More likely would be a Turn 4 or Turn 5 US landing on Borneo or EI, allowing at least 1 round to build up some fleet for the journey, and a round to do the Pearl Counter.
So in USA4, the US lands in Borneo or East Indies, after spending at least their US1 build on fleet to get there.
On USA5, you can finally BUILD that IC.
On USA6, you can produce your first units there.
SIX TURNS (MINIMUM) to get that IC established and operational.
Now what pray tell has Japan been doing for those 6 turns that they allowed a small US fleet to move 3 turns across the Pacific, take a major island, build a factory, and strart producing there? Didn;t they bother grouping their 2 BB’s, 1-2 AC’s and some FIG’s to be able to strike that fleet somewhere along the way… oh say off Solomons? Or killing the US fleet once it arrives in SZ48 which is within range of land based FIGs and the BOM?
And then there is the issue that, about the time the US is trying to slip into Borneo or East Indies, Japan was probably already gearig up for their Australia/New Zeland operations, meaning that at least a portion of Japan’s fleet, as well as invasion forces, are already in the area to either block the US invasions, or to just re-take either of them if the US were to gain them.
The Birts can pull off an early seizure of one of thsoe Islands if everything goes right in UK1 & 2, but they don’t have the income to maintain their German offensive AND build fleet and air in the Pacific. The US has the money to build there, but takes too long to arrive.
You might as well also write about the Russian’s building an IC in Manchuria on R3… :mrgreen: