Well, at 7|2 game could last a few minutes to a quite a while, depending on the position and how quickly people move.
That said, for an upper limit, that would be good most of the time, assume 40 moves. So in 7|2 each side would have 7 minutes plus 80 seconds (an additional 1 minute and 20 seconds). Assuming both players used all their time, the game would take almost 17 minutes. In practice, it will end more quickly, most of the time, since at least one player is likely to use a lot less time.
I like to try different time controls occasionally, but struggle to understand them. Can anyone tell me roughly how long a 7/2 game will last? Any feedback/discussion of how long each time control provides would be appreciated.
cheers