Very well written!

But 

Here is an examiner's viewpoint:
To point no. one: If a student knows the subject well, he knows the answers to most questions that are asked. Selectively studying for a subject leaving out important portions will not do of course. Also knowing what the examiners'might ask is part of the art of studying for exams!

Point no. 3:I believe it is not just that day, it is one's attitude - when one  really want to win or do well one does, else there is a mental block which makes one screw up on that day even if he knows all the answers.