I use a draw board, but not for cam timing. For cam timing, I will get it as close as I can by eye, and then do a creep tune on the bow to get it into final timing position. The whole point behind timing (besides maximum efficiency) is to reduce nock travel for those weak shots where you may not execute the shot from the same position in the valley every time. This makes your poor shots hit the same or at least VERY close to the same spot as your normal shots. I'm a LOT more concerned with where the arrows actually hit from the deepest part of the valley, as compared to the back wall, as compared to the front of the valley because thats where the rubber meets the road in terms of consistency for you as the shooter.

With that said, the draw board is a fantastic tool to get a bow setup to the correct draw length, and a fantastic tool to help get your tiller settings in check. I don't have one of my own yet but will be building one soon.