Examinations are good in that they let you see where you are. It doesn't matter if you're tired, hungry, sick, whatever. You get your score and see where you stand on a comparative scale of accurateness.
Being sick or tired can be taken into account after scoring for a personal observation of how you do at your worst or so forth, but should not be used as a rationalization for doing poorly. You either know it or you don't.
When I was in junior high and high school, I was rebellious sort of course, but I was also an avid reader and interested in many things of my own accord. I would generally not do the assignments or homework, but almost always did well on the tests. Which made them both dislike me and respect to a degree at the same time. They had to pass me for I passed the tests. Even after I quit high school and one day decided to go get my GED, they pre tested me and I didn't need any prep classes or anything like that. I did well on the test.
Wisdom is whole 'nother ballgame. Someone can be very wise and practically be illiterate. Conversely, one can have a PHD and at the same time, be an idiot as far as wisdom goes. I think the difference between them is like...book smarts and street smarts, along those lines.
I'm fairly intelligent, but in no way do I profess to be wise. I may be, but I do not think that one can judge their own wisdom. That's judged by others.