It is a low Level strategy that works well at low Levels because the pitchers are wild.
you definitely shouldn't swing at a borderline pitch "on the black" without a strike and be selective looking for a pitch that is well over the plate and maybe even in a certain area if you are the type of hitter that sits on certain pitches (not everyone is that type of hitter even in mlb) but at higher Levels if you get a "Cookie" better punish it even if there is no strike because you usually only get one mistake pitch per PA against a good pitcher.
if you don't swing or foul that pitch off consistently you are not going to make it at higher Levels.