Fred,
Guys have been skyscraping since I started waterfowling on Wister in 1969...There's a few trains of thought involved I believe...One is, I paid my money, I'm going to pull the trigger...Two is the mentality, if you don't shoot, you can't kill them...Three...And I would like to think this is the most common...They just can't tell distances.
The 1st two are just plain selfish ways of thinking IMO...The 3rd can be worked on, implemented. and practiced.
ps...In my bucket is a range finder...And my furthest decoy is normally distanced at 40 yds or so...Not perfect, but does give me some reference.