After 35 years of duck hunting, I have come to the conclusion that it just doesn't really matter.
You are either in the spot they want to be or not.I now take a dozen decoys at a time and helicopter them over my head and thrown them as far as I can. I hunt them where they land.
I have found no discernable difference in where the birds land.
It drives my anal retentive hunting buddies nuts
I agree with the sentiment of your post (I think people over-think it WAY too much). It's not rocket science and I'm no duck-hunting pioneer. I've hunted with a few very accomplished duck hunters (one of whom posts here, although not as often as he used to) and I take knowledge/advice from them and apply it. The "how to" was figured out long ago and ducks are still the same ducks they were back then. No sense in reinventing the wheel.
However...being in the area where they want to land and getting them to land EXACTLY where you want them to so that you have a shorter range/higher percentage shot are two completely different things.
Think of it like a parking lot. That parking lot is where they want to be, but because of the limits of your shells/shooting ability, you really need them to land in a certain part of the parking lot, maybe even a select few spaces. If all the parking spaces are open, they'll land wherever they want. The easiest way to do that is to park decoys in the other parking spaces and leave them fewer choices. Rule out the places they are NOT going to land (the farthest spaces from the door since nobody parks there if there are better spots open). Pick their most likely landing area (generally into the wind and into the bank), then limit their options within that area and make them choose to land on your X. Now it's still their choice where to park, but they're choosing from the options YOU dictate to them.
***Except Teal. Teal are the waterfowl version of a motorcycle rider who will park wherever they want as long as there's enough physical space for their bike.