I've thought of doing this as well. I might try it out a couple times in the next week or so as well. It sounds like a great way to zero in on those curvebreaker questions that might fool you twice as the above poster mentioned.
@runiggyrun agreed. And @"Grey Warden" just breath and take some time to internalize the concept. Don't sweat it. I think if a question like this appeared on the LSAT it would be one of the curve-breaker questions.