They sure do, but maybe this figure wasn't mere play time. People certainly leave the game open when going to get a cup of coffee, go to the bathroom or answer the phone. I usually don't because I do look a the play time at the end of the game and I want a genuine number.
Anyway, if you think "30+ hours" is justified, leave it. (Not that I think you'd change it because of what *I* say, lol.)
But when I read this before purchasing a game and then finish it in 2/3 of the time despite going through it really slowly, then I'd be very upset.