DB, welcome to the board!
I think that that is the arrangement most of us find pleasing to the eye. I'd also say that it is certainly the most common setup on contemporary guns. Whenever possible, I try to center the base of the patchbox (well not perfectly centered, lets just say, "pleasingly positioned.") along the height of the buttplate, with the finial pointed to the center of the wrist.
This is certainly not an absolute. Many originals were not necessarily done this way. Some patchbox designs do not lend themselves well to this arrangement.
If you compare the two Peter Berry rifles in the ALR museum, you'll see how certain designs make it difficult to satisfy both of these rules. Both the Berry guns have similar patchbox designs. On one, the patchbox finial is pointed more or less toward the wrist and the base is very high along the buttplate. On the other, the base is centered along the buttplate, which causes the finial to point below the center of the wrist.
If I were designing my own patchbox, my goal would be to design one that would look good centered on both ends. Those are the ones that look best to me.
Jeff