Everyone knows you aren't supposed to continuously ride the brakes when descending mountainous terrain. Down-shifting is the preferred technique to avoid heating the brakes and suffering brake fade.

If you are on particularly steep terrain and have a manly 4WD vee-hick-el, you can shift into 4WD Lo. In my vee-hick-el, that generates so much drag that I can maintain 5 mph on a 20 degree slope without using any brakes at all.