What I want to say is counseling in college. In fact, in college, we still pay more attention to the pass rate of Band 4. So generally, when you take CET-4 for the first time, your English teacher will remind you of the things you should pay attention to and tell you that there will be free remedial classes in front of the school (after school). Of course, some schools will use the time of English class to train related special items of Band 4, such as listening and writing.
Every school will be different, but basically there is some tutoring.
But few people go to extracurricular remedial classes. Those are expensive and may not be effective. Moreover, CET-4 is relatively easy, so just do some exercises.