Starch is another of those 'rules' that everyone has to decide for themselves. I never use it, hate the stuff and all the other chemicals like it, haven't had any in my house for the last 25 years and even then used it only on my now ex's shirts. In 45+ years of quilting, I have had absolutely no problems at all with accuracy, squareness, precision, or anything else while making friendly or competition quilts. Starch is not mandatory in any way for precision quilting.