That way if I have exactly 2 hours to get through a game, I can then make use of the game search to find on that will work.
Surely a number could be developed but is it meaningful ? My own belief would be that precision like that is not a practical expectation.
For my own purposes, I'd probably have the time include set up and tear down.
And whether or not others carefully followed that kind of definition is an example of how the overall results would get uselessly distorted anyway.