@topwolf
In my opinion the additional set of questions in OG10(apart from the overlap with OG12 and 13) are ideal for students who are struggling with easy and medium questions. For example, a lot of my students struggle with the word problems and how the GMAT questions are phrased, and I recommend them to build that foundation with the easier set of questions from OG10. If this is not an issue for you, it is safe to skip OG10 for now and just focus on OG13 and OG12. And if you are scoring closer to the higher range of quant scores, then you would be better off focusing on the recently released official GMAT questions that are part of GMATPrep Question Pack 1 and GMAT Prep Exam Pack 1. These do an excellent job in reflecting the style and difficulty level of the current GMAT exam.
Cheers,
Dabral