Wrong. And you are calling me a liar by saying that
I never intended to call you a liar.
"BTW your July 1938 is impossible as your first build doesn't benefit from the 10 month practical."
I don't IC whore so I was using your numbers regarding that 10 months. If this is incorrect then you were the source of the incorrect data. You wrote:
"You can finish 14*3 factories no later than 1 JUL 38 as Germany. And their cost is down to less than 4 by then, and time averages about 10 months."
That clearly says that at the end of the three runs the cost is 4 and the time is 10 months. So if the first run is 5 and the time is 12 months that means the first run end in December 1936. The second run I assumed would be 4.5 and 11 months which just splits your final numbers. That means it ends in November 1937 and 10 months after that is September 1938. Therefore, if you are correct that you can finish them in July 1938 then the information about them taking 10 months must be inaccurate. But July/September is 2 months so not a really big deal is it?
Actual math for 14*3 factories for Germany in vanilla HOI3 where Germany's construction practical is 5 [with CPO]:
4.75 IC for 351 days = 1667.25 IC*days
with modified IC at normal difficulty, you get a 1.5X payback =
1111.5 days to get payback [1667.25/1.5]
which is a little over 3 years for the first batch. Then you get better payback periods for the next 2 cycles getting to around 2 years for the 3rd cycle.
Again I'll use your numbers. The first batch takes 3 years for payback. Since the run ends in December 1936 that means you don't see full payback till after 1939. Even in this best case scenario your September 1939 army is smaller compared to what you could have had without IC whoring.
And I didn't mention modified IC simply because not everyone plays on normal. I do have a question how the two techs industrial production and industrial efficiency would speed up the finish date? I mean one creates more IC and the other means it uses less resources. Or are you referring to the practicals it gives?
Also, according to the wikki the default level of practicals is 5. That means a practical level of 5 will result in neither an increase or decrease in the time and cost of building something. Germany starts with 5 so this means according to the Wikki the cost of a factory is 5 IC and 365 days. Not the 4.75 and 351 you use. Either the Wikki is worng or you are.
Finally, you like to push the practical benefit of making IC. But there is a flip side. See since you spent those early IC on industry you LOST practicals, or the possibility of higher practicals in other areas. This is just simple logic as less IC means less things built. So when you finally do get around to building those tanks, planes and ships they will be costing more in your scenario, at least for the first run or two.
Bottom line is you have the right to play the game however you want. But the numbers are clear. Building IC early results in a smaller army in 1939 then if you didn't build the IC. Or if you do decide to build the units you don't have the IC to upgrade them. Something was left out.