With standardized tests, there will always be test-takers who can get by with studying on their own. However, the GMAT is a difficult test- and usually, self-study doesn’t cut it. Studying by yourself may be convenient, but I highly recommend that most test-takers consider a course, tutor, or another resource. • You can self-study through one of those plans, and that’s different from surfing free resources on your own. They offer tech support, study plans, and more through online programs.  • You need to learn not merely the content of the GMAT, but also the types of questions and strategy. • If you can’t afford a formal course or a full tutoring option, there are some lower-cost alternatives, which I will mention in my final recommendations. • If you are determined to study on your own, please make sure you make a study plan. It takes a few months to study for the GMAT, and 30 days is simply instant enough time for the average (or even highly skilled) test taker.