Sometimes game mechanics can be healthy for the game, but bad for the show. I think special categories qualifies as such as thing.
Red boxes tended to introduce additional chaos and variance in to the game. This is probably a good thing, as the format has an enormous champion's advantage built into it. But given that the show attracted attention for the big winning streaks, too many red boxes reduced the frequency and length of those. That chaos was healthy for the show's budget, of course. Fewer winning streaks meant fewer cars.
And of course, the most chaotic categories were the ones where the player whose turn it was not to win the box. The power of that was to allow a player to win three consecutive boxes, which is why noone would take one of those unless they had to. Very game-breaking.