I did several tests, but here is a simple one to consider starting off with.
I lined up about 15 hard cover books on a table and made sure the sleeves/spines facing the camera were as even as possible.
Camera was set to "P" mode. I then put the camera with a wide angle lens (24mm) on a tripod. I set the camera to AF-S and used the center single focus point first to take a picture of all the books focusing on the middle book. The camera was about 3 feet from the books.
Then, without moving the camera, I repeated this using the individual extreme left, right. top, and bottom focus points. I subsequently made comparisons of all shots to the center point image.