Approach In Studies- Merely Covering Syllabus Topic or Understanding the Topics  

What should be a student's approach towards studies? Merely covering his syllabus topics to pass exams or to understand the topics for increasing knowledge.
I have observed that the first approach is usually the most popular amongst students. Studying only to cover their topics with no in-depth understanding of the topic and passing the exams with bright colours!! and they have done it well. Others also support this approach especially when the students have little time left for the exams or they are studying subjects of all fields ranging from science to commerce!!!
But is this the right approach? And what about the second one? Should we study the topics in order to understand it? We do hear from our teachers (If we have a good one) that you will soon realise the importance of the latter approach in your latter life.
Need to know from you people which one is better?