When I work with any hitter, I teach them the same basic core mechanics of the swing. Always of course, taking into account what kind of hitter I am dealing with... Singles/Contract Hitter, Line Drive Gap Hitter, or Pure Power Hitter. About 70% of players will fall into the middle category. Taking those factors into account I might want one hitter to tilt more and try to elevate the ball more while I might want another hitter to be more upright to match the type of hitter he is.
Some, by the way, have changed the kind of hitter they are with adjustments and other factors.
The "perfect swing" as I define it is... the adjustments a hitter makes to the pitch that he gets. Most good hitters stay within a "blueprint" of core mechanics but make on the fly adjustments based on the pitch they get and how well they have anticipated speed, location, etc.
That is why many hitters can look different from one swing to another and maybe even get the same result from those swings(say a home run). In almost every case, one can pick out a select few core movements that remain the same but the hitter made other adjustments in an attempt to get the sweet spot to the ball. There's nothing wrong with that. He/She was trying to put the appropriate "perfect swing" on that particular pitch.
Of course, those stinking pitchers
still win the battle the greater percentage of the time... "perfect" swing or not.