Hi TheGriffin,
The scoring algorithm on the Official GMAT is far more complicated than most people realize - and it takes into account far more than just the number of correct answers. Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT/mocks scores can vary a bit based on the 'biases' involved in their respective designs. If you scored a Q50 or Q51 along with a V31 or V32, then you could potentially hit 680 (although it's worth noting that your actual Quant and Verbal Scaled Scores on the GMAT probably won't be integers - they're just 'rounded off' for the convenience of providing easy-to-read information). By extension, your actual results relative to what you might see on some 'scoring tables' can sometimes be off by 10-20 points because there is a difference between a "low V32" and a high V32."
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied? How many hours do you typically study each week?
2) What study materials have you used so far? What "brands" of CATs/mocks have you used?
3) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your overall goal score?
5) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich