Basically it works like this. Day 1 - fly to AP grading site Day 2 - learn the rubric. They give you all the answers and truthfully most of my AP students could grade given the training. By the end of the day you will be very accurately grading exams and giving them the identical grade to everyone at your table Day 3-7 - grade all day in 4 quadrants and yes it can get hard at times Day 8 - Finish the grading which means you only get about 50-75. Only once have I ever graded beyond noon on this day and then you get the rest of the day to do things like do real sightseeing. Day 9 Fly Home.
So if you are interested, here is the place to sign up.