Whether it is primary school, middle school, college or graduate school, the greatest value of exams at all learning stages is to allow people to experience the psychological process from the pain of "not being able to figure it out" to sudden enlightenment.
Although due to various reasons - artificial and accidental prejudices in the social environment, etc., this value is far from being realized. Von Neumann has a famous saying:
If you feel that the test questions are not simple enough, it is only because you have not yet understood how difficult life is.
