Pete:
You describe my method as diddling or trifling with the pressure. Diddling means cheating and trifling means acting without serious purpose and I am at loss as to how you can believe these things.
You are right that when the method is fully validated and measurers are confident with it, post-calibration will be superfluous. In the meantime, post-calibration will serve as a check that it is working, i.e. if the measurer gets the same pre- and post-calibration factor, this is a good sign that he is doing things correctly.
You contend that I am “building specialized pressure-testing equipment” for my own purpose. To the contrary, my goal is to develop a method that any measurer can use with a cheap, simple, and readily-available gauge to improve the accuracy and efficiency of his measurements. I am pleased to say I will shortly report that I seem to have met my goal.