Slight spoiler below...
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The new rule lasted exactly four weeks, starting with the John Forsythe panel and ending with the Jack Albertson panel.
The contestant who chose Jack in the head-to-head wasn't bound by the rule; it was her first time at the Super Match, so she could have picked any of the six celebrities. Jack turned out to be a good choice, though, since he matched her response and the contestant won the $5,000.
While this rule may not have been the best, it still was an obvious response to the fact that Richard Dawson was getting picked almost every time -- which, unfortunately, wasn't addressed again until three years later. It's one of the reasons that I prefer the Star Wheel era episodes to the pre-Star Wheel episodes. Actually, in some ways, I prefer the '73 and early '74 episodes, even though the writing wasn't as good for the main questions, because the pattern of Richard being chosen so often hadn't been established yet, and you got to see a variety of celebrities play the head-to-head match.
Brendan