Each student has some strength and weakness. It is a common advice available to everyone that he should try to overcome his weaknesses. This shifts the focus towards weaknesses and in certain situations doesn't allow the strength to work.
It depends on the kind of examinations a student is taking. There are examinations in which lakhs of students score over 90% marks. Do such tests test the strengths of the students or weaknesses? It is basically a pressure situation in which a student has to built a capability of answering questions in a pre-decided way. If he does, he scores irrespective of whether he knows the concept or not. He gets high marks but how does it help him? High marks can be helpful only in getting admission in next course where admission is based on marks. Leave aside the marks and you find that these students in order to get high marks have build such capabilities that may not be of much help in getting success in subsequent phases of life. Mere a surface level knowledge on all the topics in the structured way provided by the system is good enough to score 90%. This habit of living with surface level knowledge and not learning to go deeper becomes a bottleneck in getting overall success at later stage.
Majority of the examinations in India that open the door of great career are low scoring. Whether it is IIT-JEE or CAT or Civil services examination, in all such examinations it is seen that about 50% aggregate marks is good enough to get a good rank. Such tests try to test the depth of understanding of various concepts in the student. It penetrates to such level that it is not easy to have such in-depth understanding in all the topics in the syllabus. It is not expected too. But, if a person follows the advise of working hard on the weaknesses, he gets into a trap. He is not able to go sufficiently deep on his strong topics to be able to score in such examinations. Also, he is not able to do much from his weak areas. It is seen that lakhs of students regularly scoring over 90% in their school and college examinations fail to score even 20-25% in examinations like IIT-JEE. That too after coaching from highly reputed places.
Hence, it is very important to work on own strengths and allow them to work for you. Shifting the focus from weaknesses to strengths works wonders. And it makes the preparation enjoying too.