Actually, there can be a definite difference in pattern spread at 15-20 yards, depending on several factors. At 10 yards not so much, but even when ruffed grouse hunting few shots are taken at 10 yards.
Quite a few experienced ruffed grouse hunters prefer a double-barrel with a VERY open choke, combined with a much tighter choke. This was the combination suggested by the late Frank Woolner, a good writer very experienced in hunting ruffed grouse in New England. The reason for the tight-choked second shot was to make sure enough shot got through leaves to kill a bird. After trying this combo myself I like it too, and have hunted ruffs (and other forest grouse) in several states and Canadian provinces.
But I will also note that pattern spread also depends a LOT on the load, in fact often far more than choke. This isn't exactly secret information, but unless somebody actually does pattern their gun it's hard to comprehend.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
