I didn't know what it was called, but that's exactly what I do going down steep grades, Melissa. I have driven standard shift cars most of my life so I routinely downshift, but on some hills that is not enough. So I brake to slow down enough to get control and then let up to give my brakes a chance to cool down.
I once had a scary situation in my Chrysler minivan going downhill in the Smoky Mountains. I braked going around a corner and the vehicle started hopping. It was literally moving up and down so steering was awkward. I might have been going a tiny bit fast but I was not out of control until the hopping. I slowed down to almost a crawl because brakes started feeling really rough. I had to replace brakes and out-of-round disks when I got home.
That was many years ago. Motorhome brakes have been terrific. Thanks for your expert soap box and giving us the term for that technique.
I learned to drive way back in high school on a standard transmission because that was all our high school had--one old beat-up station wagon with a stick shift and transmission that had suffered through a lot of kids!