It's possible to record mission records during full campaign runs like I do for the rest of the series. After looking at some runs I noticed something: For the times shown on the graph at the end of a mission, the right-most time is consistently about 28/31 (~90.32%) the length of the actual game time. With some added buffer (like rounding up and adding a second), attempts that don't show the stats tab at the end could be included on the IL board.

I've already gone through all the campaign runs to get the mission times. The sum of game time (for Easy) comes out to 1:30:36 for Soviet, 1:35:56 for Allied, and 1:45:24 for Imperial. Including the Hard missions puts it down to 1:09:38 for Soviet, 1:07:49 for Allied, and 1:03:58 for Imperial. I have real time (or as I call it in-game RTA) recorded for each mission as well.

Excellent spot! I've just tested this with some of my videos and it does work.

Regarding the 'buffer' though, from what I've seen it looks like rounding up does the job just fine. What would be the need to potentially add 1 second on top of this?

Just a safety measure. If you think it's accurate enough then the extra second doesn't need to be added.