First of all OG is made for the average student, inside the so called "bell curve"
Moreover, it is not adaptive. That say, is really important to learn the concept behind each question and through your reasoning try to disentangle a question, appliyng this or those concepts to other similar questions. Is not a simple to learn a concept and apply .
The gmat in not an exam "at the end of the book" but each question is like a onion: different layers to eviscerate. Sorry, an advice, your is not the right mentality
You must understand what's going on always, try and prove, make an intuition even before to read the question itself, already know what is tested on the situation at end.http://www.beatthegmat.com/mba/2011/02/ ... ngineering
If you need something do not esitate to ask
KUDOS is the good manner to help the entire community.