It should I guess, but you shouldn't rely on it as you'll most likely end up with a blank black screen if you don't double check.
With a 2 monitor setup it's much easier to see if it's capturing properly, 1 monitor setup and it gets a bit tricky; Basically forcing you to alt tab, select the game, and then go back in the game. However even then it can still capture a blank black screen depending on the game and version of OBS.