I figure that if you pepper the hell out of a snag, you are educating the fish on that particular lure and retrieve you are using. Mostly if thye fish has not taken it in the first few casts he either is not interested or your retrieve/lure style is not appealing. Why educate them intensively into ignoring future presentations.
I mean if it was you and there was this particular flashy lure comes past your nose 20 times and you eventually take a swipe and it stings the hell outa your gob I would doubt you would ever touch anything resmbling it again.
Jack.