It's not necessary. Enrolling in classes is an auxiliary training method, which can help candidates prepare for exams better and improve their test scores. If candidates have a good foundation and ability and are familiar with the content of the exam, they can choose to prepare for the exam independently and not report for class. If candidates are not familiar with the test content or need to improve their test scores, they can choose to enroll in classes and improve their preparation level through professional training and guidance. It takes a certain amount of time and money to apply for classes. When choosing to apply for classes, you also need to choose a formal training institution to avoid being deceived by some bad training institutions.