Firstly, the success cannot be evaluated by exams because some people are theoretical while others are practical. Some people have photographic memories, others are amazing with memorization. Some students can study for weeks and not understand anything, some students learn so much better with the hands on approach, others do better by simply reading. For example, some students are smart in school or university and get the highest marks but when they start to work they find it very difficult to put their education and knowledge into a practical use. Unlike others who do not do well in their studies but are successful in their jobs. Exams just test people's memory. They do not test their intelligence and ability to apply what they have learnt to solve practical problems.
Secondly, the medical condition or social situation before the exam can cause failure. For instance, many students sometimes face sudden illnesses that may require surgery such as appendix, tonsils or accidence resulting in broken limbs. Others might have family problems such as divorces between parents, living with stepmother or stepfather and losing something valuable. For that reasons, when students face such external circumstances resultant poor exam score. These would then give an inaccurate reflection of students progress and learning abilities. Furthermore, exams give too much stress, panic and anxiety. They may destroy students when they are forced to worry about nothing else but a grade or