Depends, if the person behind the rifle is doing everything wrong (from trigger control, breathing, hold, pressure, etc), large group sizes can be explained. But if he or she shoots well with one springer, and crapy with another, a problematic rifle, bad pellets, or what ever other reason, might be the cause. If you look at the premium brands like Air Arms, Feinwerkbau, Diana and Weihrauch, these things are accurate, period! Those cheaper brands like Hatsan and Gammo, you can get lucky with those, but lemons with these are more common than the standard. Been there, done that, never again! But even with those cheap a$$ brands, I'm still able to shoot tighter groups than what you mention Ray.
But... there's always a but! Mr. Tom Gaylord, the person who came up with the Artillery Hold back in the 90's, is someone who is highly respected in the airgun community and who deserved his stripes. To just say that what he has discovered back then is BS, is like saying that Neil Armstrong knows dick poope about landing on the moon.
Oh, and what most people want is high velocity, the higher the better. But they forget that those magnum rifles that shoot faster than the speed of sound are inaccurate as hell because of the ballistic problems that come with pellets entering - and exiting - the sound barrier. Want to talk ballistics? Just see what happens to a pellet with the ballistic coefficiency of an ice cube, once it leaves the sound barrier. Do I hear someone say 'pellet wobble'?