Every product photograph is made on a model of about 178 cm. Almost no one is 178 cm.
Every one read against your measurements rather than the model’s.
IIThree numbers off a product page. The garment then has a page, for everyone.
IIIWhat each fibre does, what it is good for, and where it lets you down.
IVWhich cloth suits which garment. Summer tailoring is wool, not linen.
VGrading, ease, stretch, and the one place the golden ratio is truly in the body.
VIBrands know all of this. The reasons they do not act are structural.