How to properly adjust Look Keo pedals
If you're never walking on the cleats and can track-stand at junctions and traffic lights they should almost never wear out. 

There is minimal wear clipping in and out. The reds are 9 degrees of float before unclipping which may increase the wear though. I use the black cleats (0 degrees) and I wear out the bottom of the cleats through walking and stopping/starting long before I wear them out from riding. In fact, I'm on only on my second pair in 4 years.