Wide feet
Retail width grading is coarse and inconsistent. Most brands offer one width, a few offer two, and the extra width usually arrives bundled with extra length you do not need. So you size up, the heel loosens, the ball of your foot sits behind the flex point of the shoe, and the shoe creases in the wrong place from the first wear.
Width and girth are measured directly at the joints, then the last is cut to those numbers at your actual length. The flex point lands where your foot actually bends. No sizing up to buy room, no trading heel fit for forefoot fit.