theres no rule saying you have to, but its not a bad idea. d-tuning edges will make sliding a little easier, but not a whole lot. The one this it will do is keel you from getting hung up on the little imperfections in the rail. cathcing these little ruts and shit can also rip your edge off the ski. i guess if you wana really round em off good you can just use a metal file, but you can just go up to the rail an role your edges over it, that will round them off good. If you, make sure you do it where nobody will be silding one it, like by the ground, cuz that will just cause more imperfectons which suck major balls.
'what are you a mountainier, hes gat ropes and shit hangin off him'