The main reason I didn't finish the exam is because I obsessively look up everything about which I have the slightest doubt in the dictionary. And that uses up all my time.
Plus, it's very humbling to go from a class of 6 to an exam hall of 40, and to be the only caucasian in the room. Especially after my Korean friends had just finished telling how close Japanese and Korean are and that that was why most of the people studying Japanese were Korean. I'll be honest. I was shit-scared.