[nicklecompte]

> I'm not sure I agree that those rule-of-thumb statistics are "arbitrary" or "fictional"… I guess it depends on what you mean by that.

Sorry for the confusion: I meant that fragmede's comment was arbitrary and fictional, not the 90% figure. I was talking about these numbers:

  if it takes 1 hour to get one answer by hand, but only 20 minutes for the machine, and 20 minutes to check the answer, the user still comes out ahead

[jamesbrady]

Oh, my bad—I misunderstood, thanks for the clarification