>How often should the wearing points that you speak of be reasonably maintained?

As soon as they exceed certain tolerances, which you have to determine either through experience or EMD's specifications. And, the maintenance forces not only have to check the "shock absorbers", they have to install them correctly. "This Side Up" doesn't mean "This End Up". Nor can you use passenger car shock absorbers for locomotives, even though they might look the same. I'll be willing to bet that the transverse shocks on the Amtrak F59s have never been changed since they were installed at the factory.