To put it simply, the GMAT tests your ability to analyze. However, you can’t analyze much of anything without a whole lot of background knowledge. It’s undoubtedly true at your workplace (even if you take your background knowledge for granted), and it’s probably the case in just about every aspect of your life.
Knowing what I’ve just told you shouldn’t drastically change your study approach. But instead of viewing foundational knowledge (formulas, grammar rules, etc.) as the be-all end-all of your study time, view it as just that””a foundation. You can’t engage in creative thinking about an algebra problem if you don’t know how to FOIL a quadratic, and creative thinking is often the difference between a 600 and a 700.