If I recall correctly, Brad Rutter also used spaced-repetition and actually built a replica of the Jeopardy buzzer system to practice buzzing in as quickly as possible. He is the highest winning game show contestant of all time.

In 20 regular season and tournament games, Rutter has never lost a Jeopardy! match (though he twice trailed at the end of the first game of a two-day match before coming back to win in the second game—against Rick Knutsen in the finals of the 2001 Tournament of Champions, and against John Cuthbertson in the semifinals of the Ultimate Tournament of Champions).

He did lose against Watson, though.