It shows the shrinkage that does occur in time. You can also see how the panels have shrunk and pulled out of the upper channel. I've had to brace them.

You can also see the second 2 x 4 that I added at a much later date.

I do not paint redwood because you then have to repeat it every few years, which is expensive, time-consuming and boring! The paint you see was the neighbor painting his side!