Same here man, I don't see the point of being able to do math for dental school, and I honestly don't think dental schools care either.
I've done math destroyer up through 6, and am going to do a few timed 2 days before my test and just call it good...I'm one of those people that just isn't good at math, so slaving over it for days and days isn't going to help me any.
As for your question...the tests are pretty repetitive and spread the types of questions out well, so completing up through 10 and then repeating is up to you...but I don't think it's absolutely necessary.
