When my engine brake engages it downshifts to 4th if I'm going slow enough. I've learned to hit the top of hills at the speed I want to descend. That speed is generally between 45 and 50 because my coach will be approaching 2100 RPM in 4th at 50. Generally my coach Jake brake will hold the coach under 50 on 90% of the descents I've encountered out West and on the way to and from Alaska. If I have to brake on a descent I will brake relatively hard for a short period of time letting off the brake so they can cool. When descending I generally have to accelerate periodically to maintain 45-50. Most important points, speed at top of hill low and brake hard for short periods, do not ride the brake!! Hope I'm not telling you stuff you already know. Good luck!!