See coaching has a very minor role in gate preperation. Each and every one of us has studied all of our subject in one night just before our semester exams which had numericals comparable to good questions of gate. So we are capable of understanding the topics on our own. But the biggest question is what to study and how to approach that question. Here coachings play an important role. They give you direction. And we all have seen gateforum has given a lot of good ranks. So no matter what there is no fault in coaching institute. There might be some mistakes in their material but for gate previous year questions are more than enough. You can prefer made easy previous year questions book if you find mistakes in your material. But in the end it all comes to your hard work. how many times you have completed that previous year book. Made easy has approx 16k students in mechanical itself..and approx 600 of them come in top 1000.( just making a guess here). So its not coachings fault..Trust your teachers and the institue. They will do their part to 200%.. but you have to give your efforts as well..Work as hard as possible without predicting and calculating the outcomes.. No one is sherlock here. Just work hard and let universe play its role…