No vanes here, but I used to shoot off the shelf, and arrow flight was lousy... porpoising that wouldn't go away. Someone well-known in the bowyering world asked me if I had a callous on my string-hand 4th finger. When I told them I did, they told me that was indicative of a high elbow, and therefore causing downward movement on the shaft at release, resulting in excessive contact at the bow shelf. They suggested to try shooting with a rest, so I did... and my arrows flew like darts immediately. I've been using a rest exclusively since at least 2007, and have never had one fall off or get damaged. It is odd to me that so many poo-poo them.