Before I started on the TT, I had NO IDEA how labor intensive it is to give an exam in a large class. Writing a fair exam for the first time is difficult (which I expected), but I had some help from a colleague who previously taught this class so I could see about what level to aim at. The grading takes a while (especially grading 200 exams alone--yikes!). But what really gets me is all the overhead.
The first annoyance is having to have 4 versions to cut down on the temptation to cheat. THis is pretty annoying, even though it just involves scrambling the questions. Making up the multiple choice exam keys for the grading machine is pretty annoying as well.
On or shortly before exam day, I need to: count the printed exams to make sure the numbers are correct, check the exams for typos/printing errors, meet with the proctors to go over the ground rules, alternately help and turn away desperate students, make sure I have a seating map for the room so I can post a seating chart 15 minutes before the exam starts, make said chart, distribute the exams with the proctors, walk through the exam a few times to answer mostly inane questions (as in "How do I do this? Sorry I can't tell you."), collect the exam, count the exams to make sure we have them all, and then submit the multiple choice part for grading. I also get to listen to all kinds of excuses for not showing up, complaints about how hard the class is, and whines about how hard they worked even though their grade doesn't show it. I actually like the grading part, and it is fun to help out the conscientious students. I didn't know any of this on the day I found out I would be teaching 200 non-majors this subject.
I also had no idea how nervous I would be for my students!