Personally I think for a good number of 3 point shooters it depends on where they get the shot from, and whether they are stepping into the shot or shooting it set, off a ball fake, off a right hand dribble and such. There are clearly spots and rythyms for most players that are comfort threes when open. Teams of course scout the 3 point shooters and attempt to take the comfortable 3 away. Shot charts can be useful for this of course as well as video.

So the variation from year to year might have something to do with where and during what situations guys are getting their 3's, especially with diff. coaches and teammates. Imo there are clearly teammates on some teams that do not recognize or care where and during what situations a good 3 guy is getting three point shot from.