Card Orientation in Holders

jmmiller777

So, I was blowing through some Mantle listings on the bay and found different orientations on the way horizontal cards are slabbed. My question here is this: why are some cards always slabbed with the label on the right, and other cards are set with the label on the left, and still others have a combination of the labels on the left and right? Horizontal sets appear to always have the header on the right. I didn't look at a bunch, but the World Series subsets from 60-61 seem to have no set orientation. Any ideas here?