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From the earliest exposure, kids are allowed to mimic the 'big leaguers' in their approach. This can and should be fixed by umpires and coaches from the start. (I remember Nicklaus being blamed 20+ years ago for his slow pace of play...which was then adopted by the majority of new players as 'the right way to do it'.)
And that most of all concerns batters stepping out-even though they're not supposed to anymore. Baseball can fix pace of play if they want to.