I always seem to have a problem with jacket (typically blazer type) shoulder fit. I think it's because I have a narrow but somewhat square shoulder line, and not enough deltoids!
First have to balance shoulder, chest and hip and those modern skinny armholes-- a tall order, because if I size down too much for the shoulder area, everything else pulls.
A slight shoulder pad works well for me, and straight shoulder lines, more so than cocoon-y styles. But, if the shoulder padding is "sharp", meaning has a straight-edged pad lined up at the seam, the slightest overhang makes those shoulder dents--sometimes even if no overhang but lined up with my shoulder bone edge. So the best shoulder pads are those that are very minimal and are slightly rounded over the edge--not very common.
It's pretty easy to see when things are WAY off with major overhang--haha, I can sure tell it on other people-- but I've about given up on the perfect, "invisible" shoulder edge; especially with movement--things look fine maybe with military posture but then when you move arms, get that shoulder dent going.

Solutions are:
--more lateral deltoid raises
--no-pad jackets
--change shoulder pads--something I find difficult in terms of finding the exact fit for the jacket, and also expense, if lined
--identify some amount of acceptable dent/overhang--maybe I'm too sensitive and there's always some? I'm not talking about those linebacker looks.

Any guidelines or practical approaches appreciated.