Well, attending a prep school helped me improve my scores back in the day. And I can tell you that being there helped a lot of people. But it doesn’t help everyone. The reason for that is simple: a prep school doesn’t improve your score. A prep school helps you study, and studying improves your score.
That distinction may seem like splitting hairs, but it is important to dismiss the notion that you can just pay for the course, attend the classes, and expect your scores to improve. They might if you at least listen to the students, but I saw plenty of teens completely ignore both the classes and the course materials because they didn’t care to be there. And they didn’t improve their test scores, of course.
I would suggest you figure out how to study on your own using resources like this one. Whether you’re studying for the GAMSAT or any other test, putting together your own study routine and following it for a few weeks will help build the foundation you need to improve your scores. Then you can help boost those study efforts by attending a prep school and leveraging their teachers, training materials, and test exams.