Peek Index?

I have seen pictures of several card-manufacturer's version of a dual index card known as a "Peek Index" or "Poker-Peek Index". While I am familiar with its use, and why,, one design aspect escapes me. It seems that the Peek Index is always represented as rank over suir, (as in the regular index) and in some cases diagonally printed. What I haven't seen is the rank superimposed upon the suit. As far as being a "Peek Index", it seems to makes sense. Is there some reason (design patent I guess) the rank/suit cannot be illustrated this way? The only difficulty would be printing the "10", but that could be altered to "T".