Sorry. I'm sure I was more crabby this morning. But, it is awfully tempting to get in the "within" 0.001 debate. Harder yet to get into what one can "feel." Being trained to palpate (feel biologic tissue skillfully) we used to practice finding a hair under 200 pages of the Guyton's physiology book. I can tell you some could feel more than others.
"Within" 0.001 seems to me to be +/- 0.005. If it were to be +/- 0.001 that would be a spread of 0.002, or "within" 0.002. (There, I got he pedantic part off my chest ).
I do agree with the 3-blade method. And the requisite air-cooled VW Beetle training. ("When you can adjust the VeeWee's valves on youir back in the dark and rain, you can have a Guzzi, Glasshoppa. )
I'm shocked no one has yet used the phrase, "stone cold."