That was Watson's big advantage -- buzzer speed. If Watson was able to get to a high enough confidence level within the four to six seconds of the question being read, then Watson was going to be faster off the buzzer than either Jennings or Rutter. The only time Watson WOULDN'T be fastest off the buzzer would be if it was still in the process of choosing an answer. If it was a question that all three contestants knew, Watson would buzz in first.