1. Weak self-study ability: If your self-study ability is weak and you need professional guidance and counseling from teachers, it is a good choice to enroll in classes.

2. Time is tight: the preparation period for postgraduate entrance examination is long. If you are pressed for time and want to improve your grades as soon as possible, then joining classes can help you review more efficiently.

3. Lack of study plans and methods: If you don't know enough about the review methods and plans for the postgraduate entrance examination and don't know how to make a suitable study plan, then you can ask the teacher to help you make a suitable study plan.

4. Need professional counseling: If you have great difficulties in a certain subject and need professional teachers to provide counseling, then applying for classes can help you in this respect.

5. Want to get more resources: Enrolling in classes can expose you to more postgraduate materials and information, which will help you prepare for the exam better.

6. Want to know like-minded students: Enrolling in classes can let you know some like-minded students, and everyone can encourage and help each other and make progress together.

7. I want to get psychological support: I have a lot of psychological pressure during the postgraduate entrance examination. I can give myself some psychological support and encouragement when I enroll in the class.

In short, when choosing to apply for classes, you should judge according to your actual situation to ensure that applying for classes can help you prepare for the exam better.