Arch Supports; buying over the counter is harder than just knowing your shoe size?

As shoe fitters, too often we come across ill fitting over the counter arch supports (OTC). It's easy to walk into a store, see a size on a package that looks like your shoe size, buy the product, then throw it in the shoe and away you go. You may even find some temporary relief, because something is better than nothing, but alas your pain returns or it just doesn't quite go away. So, off you go on another quest and you repeat the process. Besides the fact that upwards of 85% of people are wearing the wrong size shoe to begin with here's the issue; your arch length and shoe size rarely are the same. In fact, it's not uncommon to go 1, 2, sometimes even 3 sizes larger in an OTC than the measurement of your shoe size. This is why, as shoe fitters, it's vital to make sure we fit the OTC just like we fit our shoes by starting with a proper measurement and then assessing the fit of the OTC to each foot. Have played the ill-fitting, pain never goes away, OTC game? If so, what are your thoughts?