I'm shocked -- even as a primetime show -- they want to offer such a big time advantage to the contestants, even when they go for higher stakes.
I think there are two things to keep in mind:
One is that, just like in the main show, each level translates effectively into "how many wrong answers do you want to afford giving?" Assuming around 6 seconds per question/answer combo, a 10-second cushion leaves maybe room for 2 wrong, but...
The other thing is that the contestant
always goes first, so if both sides have the same clock and are perfect, the contestant will almost certainly lose, so for non-Super Offers there needs to be a little bit of a cushion for that, too.