During the course, the 7 study guides are almost entirely used for homework - you don't even bring the books to class. You study the upcoming topics before a certain class, and then we spend class time learning how to apply the principles in the books to actual GMAT questions under timing constraints. So, for instance, I don't spend much class time teaching people how to solve equations or factor quadratics, or that kind of stuff - it isn't a traditional math class.
The most common thing we do is actually work through OG questions - I give my students a certain amount of time to try a question first, then we go through and pick it apart until my students know exactly what's going on, how to do this problem in 2 minutes, how to recognize a problem of this type in the future, what the shortcuts are, how to make an educated guess if necessary, where the traps are and how to avoid them, and so on. Throughout this process, my students are learning strategies for how to tackle the test overall and each individual question - and that's everything from content strategies to question type strategies to timing strategies to test-taking strategies.
The books will give you a lot of great info, but the instruction is what allows our students to earn phenomenal scores on the test. Not to go too infomercial on you, but our students' median score on the official test is a 710.

We don't, of course, track scores for people who just buy our materials and study on their own... but I would be extremely surprised if the median for that group was in the 700s.