redmark wrote:I've seen some people post on BTG that they used OG11 and OG12.

Isn't there significant overlap? I have both books.... I was wondering if this would be worth going over both books. I have the time to go through them both. But is it really beneficial?

Thoughs on this please....

Yes, I think it is very much beneficial for one aiming to crack the GMAT with elementary tools provided in OG-s. I finished review questions for Quant in OG11, and now I am doing OG12 problems. In fact, OG 11 was kind of introduction and the learning domain to me. OG 12 is the battle area where I desire to solve and scrutinize each problem for Quant.

The 12th edition contains about 1/3 new questions. One area of significant change is Data Sufficiency were there are more questions in the 12th and about 50% are different from the 11th edition. For other sections about 25% of questions are different.

I would suggest that as you go through the 12th edition that you skip the ones that you clearly remember. If you do not clearly remember it then it does not matter if it is new you should do the question. No doubt you will not remember all of the questions, especially on the Quant side.

Overall it is worth looking at the newest material available which is the 12th.

Good luck!