Students often feel that one has to spend a lot time to study for competitive exams. This is actually a misconception. Let us take the particular case of JEE Adv. The IIT system has long been critical of the student quality which has been entering the IITs. The main reason for such a grumble is the dissatisfaction with coaching industry which is depleting the students of their creative potential and making them dullards, selfish with no desire to serve nation and God. To counter this system JEE Committee has been trying various means of fighting the coaching business and over the years the exams have increasingly become oriented towards conceptual understanding rather than calculation or rote based learning. Understanding this an intelligent student would better spend his time in comprehending and internalizing the concepts rather than just spend long hours memorizing formulae or merely do more problems in a brute force manner. This is not to say that one should neglect solving problems or memorizing formulae, but they should not be prioritized at the cost of grasping the essence of the subject.
Also instead of being result oriented a student would do better if he/she studied being duty oriented towards God.(BG 2.47)  As the famous saying goes – Don’t run behind success, run behind excellence and success will chase you!