Hi JGallimore,
If you took these CATs in a realistic fashion, and we assume that the scores are accurate, then you could have very easily scored 630 on any (or all) of them. GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. Assuming a similar 'swing' in how your CATs function, your 3 CAT score results show that you essentially performed the same each time (about a 600 +/- a few points; with a "high end" of 630 and a "low end" of 570). To hit your goal score, you do not need to correctly answer any questions that you think are too hard or too weird, but you do need to keep the little mistakes to a minimum on the "gettable" questions.
I have a few questions about how you took your CATs:
1) Did you take the ENTIRE CAT each time (including the Essay and IR sections)?
2) Did you take them at home?
3) Did you take them at the same time of day as when you plan to take your Official GMAT?
4) Did you ever do ANYTHING during your CATs that you can't do on Test Day (pause the CAT, skip sections, take longer breaks, etc.)?
5) Did you ever take a CAT more than once? Had you seen any of the questions BEFORE?
Beyond those questions, I'd like to know a bit more about your timeline and goals:
1) When you say that you're trying to get into Business School "at the last minute", what does that mean exactly? What application deadline(s) are you facing?
2) What's more important - getting into (any) Business School now or getting into your first-choice Business School (even if that means getting in a little later)?
3) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich