Is the Schiller Cape PE Really Predictable?

The Schiller Cape PE has been wrong so long that anyone should know not to use it for any kind of even intermediate term timing. I think going back to 1993 Cape has been above its long-term average for 90% of the time. However, if you take the average Cape at 15 or 16, if you're buying stocks when they're at above average valuations, your forward expected return should be below average. When you're buying Cape at below average PE, your forward expectations should be above average.