My reply to this is, again, consistency. I always thought as long as you are consistent in your cutting using the same exact lines.... doesn't that make it all relative??
Am I crazy to think as long as you are consistent throughout a project everything will come out fine?? I certainly haven't had any issues doing it this way and I am really picking about precision.
And, as someone else said, I am sure Jenny is using this method as it would be the quickest way to go for a video piece.. JMHO