Hi kri1311,
The OG from the last couple of years has essentially been the same set of practice questions - and prior versions (going back to the GMAT2015) typically replaced just 10% - 15% of the practice questions. By extension, you would see lots of 'repeats' if you went from one year's version of the OG to the next year's version. However, if you only used a recent version (such as the GMAT2021), then you would likely see lots of questions that you had not seen before IF you jumped back to a much older version (such as the GMAT2015). That all having been said, while the OG books are great sources for practice questions, they're not designed to teach you Tactics, patterns or the little 'secrets' behind the GMAT - for those, you'll need Course-oriented materials.
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 (or approximate 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