If you seen my Photography composition guide, you seen that centering a subject is great for composition, if you want to show off symmetry. But if you shoot something like this you have to center it perfectly. If the symmetry is even a little bit off, it will look very distracting in the photo. I always try to find something on the ground, to center the camera on and then use live-view with a grid overlay. Having the camera perfectly in center is a little more important, as if its to the side, it’s much harder to correct it in post-processing.