This is a cool exercise, but there's a broken assumption. Or an assumption of no outwear I missed:
> Where is there enough support to prevent items swinging around uncomfortably?
He answered this with a box basically around the thighs, but I'd also add the torso and maybe even the upper arms.
A personal bugbear of mine is jackets without internal breast pockets. When you have one on each side of a jacket that isn't ultra lightweight, it fits a wallet and phone perfectly, it's super accessible, and it doesn't change the appearance. In San Francisco where you never really need to zip/button up your jacket, it's perfect. This is the hill I will die on.
I think it can be quite hard to make a jacket which won’t sag too much or have a weird weight distribution with things in the breast pocket. And you may get a visible lump depending on the size of the item and fit of the jacket (again large flat phones against a not-flat chest doesn’t help, and neither does the trend for clothing to fit quite tightly).
That said, I agree with you that internal pockets in jackets are great (though obviously it can be harder to access the contents once you have taken the jacket off).
I do also have a jacket with a pocket on the upper sleeve. It’s tiny and weird and basically useless and I’m not really sure what it’s for (credit card? Tiny MP3 player? If it were a skiing jacket then I might guess it was for a lift pass but it’s definitely not a skiing jacket and it’s a weird manoeuvre to try to get your upper arm to a reader at waist height) though sometimes I will put my keys there because their lumpy shape makes them uncomfortable in pockets closer to the skin and I rarely need to access them
External breast pockets work okay for this, too, provided they're big enough and have some kind of flap (with a button or velcro or zipper) to keep it closed. Such pockets are especially handy on shirts.
> Where is there enough support to prevent items swinging around uncomfortably?
He answered this with a box basically around the thighs, but I'd also add the torso and maybe even the upper arms.
A personal bugbear of mine is jackets without internal breast pockets. When you have one on each side of a jacket that isn't ultra lightweight, it fits a wallet and phone perfectly, it's super accessible, and it doesn't change the appearance. In San Francisco where you never really need to zip/button up your jacket, it's perfect. This is the hill I will die on.