Jordan's written "setting things up for the next book" novels in Wheel of Time before, and even did a good job of it onece, which is why many people don't realize that Lord of Chaos (book 6) was one. And while the prose in The Path of Daggers (book 8) wasn't great, at least something happened. But I can't think of any tangible way that Crossroads of Twilight advanced the plot at all.