As a person of not-unlimited means, I have had to become a student of clothing's decay. I see now why fin de siecle gentlemen wore removable collars and cuffs: they simply wear out faster than everything else.
Take the cuffs on this Brooks Brothers shirt, which fits admirably elsewhere. With French cuffs, the inner facing seems to take the brunt of dry cleaning and puckers with time. As a result, the cuffs tighten, the leading edge holds a poorer fold, and the trailing corners splay outward.
The other problem with shirts, at least for me, is that the sleeves tend to shorten. I love showing a bit of cuff outside my jacket sleeve, so even a beloved old shirt will eventually give up the ghost in that regard.
The piggy bank is being repurposed toward down payments and other such adult outlays, so for now, there will be no custom shirts. Paul Frederick remains adequate for my needs.