ran into that problem a few years back on public lands, every joe was out there calling like crazy, some were good some couldn' t call home if you dialed the digits for em , the ducks just were shy of any calling cause of it. ducks aren' t that dumb and learn fast so in those situations if you don' t do what everyone else is, it generally leads to much better different results.
That year i just brought 8 or 9 dekes in with me found a quiet little nook at the edge of the land i was on ,set em up in front and then sucked back into some weeds at the shore, diudn' t call once and i' d hear the other fools calling like mad then some skybusting and within a few mins i' d have a small flight lining up at my dekes.....walked out of there with 3 or 4 ducks each time i went( which is all i' ll shoot at a time, its a long walk out and i' m lazy )
so i guess the moral of the story is ducks can be conditioned in heavy hunting to avoid calls , so find what isn' t working for everyone else and DON' T do it !!!