There are a lot of variables. Some skis, although the same model, are more durable than others. Also, it depends on your rail skills. If you are just learning how to grind, your stance wont be as good and your skis wont be as smooth to the rail. Another factor is the type of rails. For example, a straight flat rail will do minimal damage where as a 20 foot gap to rail or a rail, 1 foot drop, rail again will do much more damage. So really, it all depends.
Logic Headware....temporary site is up, its about to blow up. where will you be?
'rap aint about bustin caps and fuckin bitches, its about fluency and rapping ingenuity' Del