Thank you all so far, for your replies.
The purpose of finding the time span for an OOB G40 game - or modified G40 version - is to compare to the time span with the Axis & Allies Global 1940 House Rules Expansion.
It seems that the time spans are identical for both the OOB G40 game and the Axis & Allies Global 1940 House Rules Expansion (aka G40 HRE).
An average G40 HRE game lasts an average of 11 rounds - 1 hour and 10 minutes for each round - 12 to 13 hours on average.
This is true even for new players who are only partly familiar with the G40 HRE.
In other words; it takes the same amount of time to complete an OOB G40 game and a G40 HRE game.
