That's definitely how I see it. If I want to use Reposition, I just roll my dice, and hope to score enough successes to get to the Reposition result. Once I have enough for that, it doesn't matter if I get any more successes - any extra ones are lost. So it feels really nice to get exactly the right amount.
Using Reposition basically means that you choose to end your damage tree at the Reposition result. So it's like rolling for successes for a gladiator with a 5-deep damage tree. If you roll 5 successes, you get max damage. If you roll 6 or 7 successes, the additional successes don't mean anything, you still only get max damage. It's the same with Reposition.