Yeah, the idea is that you can keep rerolling as long as your total is below 7. You could even tier it further, like:
=< 4: Weak Hit
5-6: Strong Hit
7-9: Miss
10-12: Super Hit
13-15: Fumble
16-18: Mega Hit
19-21: Failure
22+: Ultra Hit
The idea was, like... imagine a superhero game, and you're in a situation where you're about to unleash a powerful attack against the villain, but if you're not careful, you could destroy the city. Or you're a wizard using a powerful spell, but lose focus, and you rip a hole into reality.
It's supposed to simulate this idea of unleashing awesome power that you can hardly contain.
Storywise, the group might agree that the current threat is too powerful, a Strong Hit would only hurt it, but an Ultra Hit might remove it in one fell swoop. But are you willing to take that risk?
Another, slightly more crunchy idea was to different matrices, or even just lists, good and bad ones. A Weak Hit means you do it, but you also roll on the Bad List for a consequence. A Strong Hit means you do it without consulting a list. A Miss means you roll on the Bad List once, a Fumble makes you roll twice, and a Failure thrice. Same for Super Hit, Mega Hit and Ultra Hit and the Good List.
You can also combine this with using traits: If you don't utilize a trait, the best you can do is a Strong Hit. Use 1 trait, you could reach a Super Hit, but 7-9 would still be a Miss, and nything higher than 12 would be a Fumble. And so on.