Rock roll with multiple dips

I have a pretty good handle on rock rolls that have smooth changes in gradient, but have been struggling with rolls where there are multiple moves or dips on the way down. I've been practicing this roll, which is steep and jagged and has 2-3 spots that pitch down, and it feels like I use up my arm travel on the first one and am getting thrown off the back of the bike by the end. On a shallower or longer roll I can usually reset back to bent elbows after each dip but haven't had success doing that here. Any advice?