Here goes my two cents. Having been quilting for more than 40 years I have had my share of mistakes. We all have to remember that fabric is not a stable medium. My husband is a machinist and works with 100's of an inch or smaller tolerances in metal. He actually has a small cooler he uses to transport parts across the shop so that they won't change temperture durring the 2 minute trip. If temperture can effect metal that much one can only imagine what happens to fabric. AT the recent Olympics races etc. were won by 100's of a second. If I worried about that kind of prescision I would still be on my first quilt.
I rely on the beauty of the fabric and the fact that it is "finished" as my main criteria for a quilt. Some days are better than others. If I served only "perfect" meals I would definately not have a weight problem.
There will always be members of quilds that are perfectionists. I have observed over the at least 25 years I have been a quild member that those people rarely finish anything.