Hi patrickwong,
To score 600+ on Test Day, you don't have to correctly answer any questions that are too hard or too weird, but you do have to minimize the number of little mistakes that you make 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 your Official GMAT?
4) Did you ever do ANYTHING during your CATs that you couldn'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 you took any of these CATs?
GMAT assassins aren't born, they're made,
Rich