Well, not BJJ (not my style), but in hapkido, it was a full day of testing, with both form and sparring. I did a few forms of Tae Kwon Do, but it is a more mixed style, like Jiu Jitsu. So we did sparring with hands, feet, grappling, ground fighting, etc. included. Mine lasted probably from 10 in the morning to about 3 in the afternoon. I had about six bouts, after the initial forms, etc.
In Tae Kwon Do, no grappling, pressure point techniques, etc, but the morning was devoted to forms and more forms (quite a few to cover at black belt level), other techniques and demonstrations. My school is heavy into Olympic TKD, so we have three one minute rounds with knockouts, etc. no grappling, though unfortunately. The afternoon was about six bouts with others testing for black belts, or with existing black belts. Then there were some specialized sparring, one vs. two, etc. One of my friends was testing for third degree on one test, he had to fight me without using legs, just boxing.
Interesting stuff. I was beat at the end of each day. Each school is different, though and I took the first degree tests, not 4th degree like Pete. Don't know what's involved in that.