I didn't get a black belt in TKD, but my black belt test in kenpo consisted of performing all material up to that point, including over 500 basics, around 200 techniques, in the air and on the body, twenty or so sets and ten forms. I had to present a thesis paper of at least twenty pages, mine was over 60, both in physical form and as part of a demonstration, as well as multiple rounds of point and continuous sparring against both students and higher ranking instructors, stick and knife fighting, and fighting multiple opponents. I had to fight three students testing for their first class brown belt (the last rank before black) simultaneously for five minutes continuously. In addition to the karate, we had to engage in regular PT including repeated breaks for pushups, crunches, squat thrusts, and superstars. We were required to demonstrate both physical proficiency with and technical knowledge of the material as well as intangibles such as indomitable spirit. All together, the test was over six hours long with one ten minute break at around the four hour mark.
I was pretty beat up by the end, but it was all worth it when I opened my eyes and saw the black belt on the ground in front of me. By comparison, my second degree test was far easier. It wasn't comprehensive, only 20 techniques, 3 sets, and two forms. Took a little over an hour. We do comprehensive tests at purple, brown, 1 black, 3 black, and 5 black.
Pretty intense, but by that time we were all ready for it. We'd been gearing up for it for months, increasing the intensity of our training as we got closer to the test, and by the time I tested I was in the best shape of my life and running the full lists at least twice a day. We fought hard, and paid for our belts in blood and bruises. Wouldn't trade it for the world.
-Rob