With the symptothermal methods, this is guaranteed. The CCL has hundreds of thousands of chart histories from the last several decades, and if the findings of this new study were an issue, I would know about it from the CCL already. These findings affect NOTHING regarding the practice of the symptothermal methods of NFP. What affects it is couple motivation. So-called NFP failures are 99% NFP foibles, i.e., the couple knew darn well they were taking chances, but to save face they blame it in the method, not their practice of it. I know this from firsthand experience with couples using NFP. When directly questioned, they ALL admit it was NEVER a failure of the method.