Circuit splits are by far the most common way of getting cert. They don't grant cert to every circuit split, but most of what they do, however...

The difference is that your point was based on a single circuit ruling, where it's pretty much required that the "another circuit ruling differently" happen before it's even possible to get to the SC. That is, unless the "another circuit" is the third or more circuit to split on the law, it won't get to the SC at all (pretty much, see elsewhere here) before there's a second, different, verdict, obviating the "unless" in the sentence I quoted. Again, pedantry.