Hollywood has much to answer for... on the other hand... If I'm ever downrange of someone with a shotgun I sure hope they're only "shotgun learning" was either on TV or at the movies...
And yes the scene in Open Range where a bad guy is hit through a thin wooden wall and is blown five feet away has to be either a high point or a low point (depends on your point of view...) of movie BS...
A sobering thought... if you're ever the guest of honor at a self defense trial knowing that many actually believe the mis-information they've seen on popular TV (and that some of those fine folks might actually be on your jury....) is the kind of stuff that might keep you up at night if you stop and think about it...