The generally acknowledged all-time chin-up/pull-up king is a guy named Alex Lowe. He was one on the worlds premier free climbers, technical climbers & high altitude climbers. Cat was unbelievable and absolutely indestructible. A legend in the climbing community. In a daily workout, which indeed lasted the entire day, he would complete 10 sets X 75 reps of various PU's & CU's. Cat did them as easy as I do bodyweight deep knee bends.
He was killed by an avalanche in 1999.