Every spread diagram assumes wind from one direction and nothing else changing. Real mornings rarely cooperate. The first job on setting decoys isn't picking a shape, it's reading what the wind and the water are actually giving you that day.
Ducks land into the wind almost every time, so the landing lane — the open water or clear pocket you want birds to commit to — has to run with the wind at your back, not across it. Get that backwards and even a perfect-looking spread won't finish birds the way you expect.
Loose and uneven beats tight and symmetrical. A hunter's eye likes clean lines; a duck's eye is looking for other ducks feeding naturally, which means gaps, a few singles off the main group, and decoys facing different directions instead of all lined up like a fence.
Keep the closest decoys inside comfortable range and leave the far edge of the spread open. That open water is the target you're actually hunting — it's where you want the shot, not just where you want the picture to look full.
Light matters as much as wind. Low sun behind the blind puts hunters in shadow and lights up the spread; low sun in your eyes does the opposite. When the two options are close, pick the setup that keeps the sun working for you, not against you.