A good way to think of this is to think about the average diameter of where your shots land. If you hit most of your shots into a 15-yard area, you can really increase the number of greens that you are hitting by aiming at the center of the green. Even if the pin isn’t located there. If the pin is tucked away in a corner, there is no reason to aim for it. At least half of your shots are going to miss to the two nearest areas of rough, increasing your score more than you realize.
Check out some of these pictures from the folks over at plugged in golf. They show a nice extreme scenario that accentuates the point by placing the pin in the corner, where it sits fairly close to a water hazard. I can think of plenty of courses that have setups like this, so it isn’t too far-fetched. Everyone wants to knock it close for a look at birdie (or a one-putt at least), but you are just as likely, if not more likely to put it in the hazard. Instead, aiming for the center of the green greatly increases your chances of lowering your score and increasing the rate of your GIR.
As you get ready to hit your shot, regardless of where you are located, where the pin is at, and what is around it, take a second to think of your personal landing zone. Imagine that landing area in your mind, and place it over the green. Start in the center of the green. If it extends to the rough in any spot while located in the center of the green, then you know you should be aiming at the center.