Casey, having spent a fair amount of time in your part of the world, I have seen many folks leave their decoys out all season I believe mainly due to the huge spreads used in flooded fields.

In my opinion, especially late in the year, the ducks are probably patterning on seeing large decoy spreads and become conditioned to relating spreads to hunting pressure.  Also, decoys that sit for long periods of time tend to get muddy and look less like ducks and more like decoys.

I have also found through dealing with tough ducks in other areas, that sometimes shrinking your spread to just a small number of high quality decoys will outperform large spreads.

I hope this helps!

John Devney