I think this is terrible advice. 1-2" of extra fabric around the chest is utterly unreasonable for a shirt, let alone outerwear. I would say 2.5" as an absolute minimum, if you're only wearing it over a jersey Tee; and up to 5" for layering. There's a reason coats and jackets are cut large in the chest. I know that a 36R duffle, for instance, will typically run to 42" in the chest. Before you call my advice terrible and unreasonable, may I suggest you measure and wear a few hundred peacoats yourself. Then you may have a different perspective and will have a basis for forming and publishing your own opinions. But to respond to your post, I said nothing about there only being 1-2" of extra fabric around the chest. The method I gave will produce a good fit. A good fit means there is enough room in the chest to allow layering of a sweater under the peacoat. It also provides a fairly trim fit with no layering. This method allows plenty of room for layering. It is not tight and is not binding. As an example, please see my post several pages back where I posted a photograph of me wearing a WWII peacoat that is a good fit. This particular peacoat measures 22 1/4" across the chest. My chest measurement is just shy of 42". This coat is a good fit, even with a sweater underneath. It isn't tight and it isn't binding; it fits the way a peacoat should fit.