Very true... Weather, hunting pressure, species of birds being hunted, percentages of juvenile birds hatched, period of the season... Etc... My impression of decoys, is that you can get away with less realism in larger spreads than smaller spreads (maybe mass numbers of decoys confuse birds?). I do not think that realistic decoys attract wary birds better as much as they do not flair decoy-shy birds as much... Motion can work for you or against you. There are times when spinning wing decoys work for you, and times when they work against you... Same with the motorized water motion decoys... A jerk cord (utilized correctly) generally is NOT a negative. Visibility is important, and those Full-curl decoys with flocked heads, although not ultra-realistic, seemed to work better than most decoys for attracting early season mallards. They stand out and look good a long ways off... They are also God-awful heavy.