one of the first things i learned years ago back in high school is there is no such thing as a right or left ski. either ski can be used on either foot. as a racer, on a race weekend i would practice and free ski before the race on one edge, and switch edges just for the races.
i no longer race, but i still keep track of which edge is the fresh edge. it is definately a smart thing to do so... cause when you put your skis down, you may find you always put one down on the right side (i.e., with the way my bindings lock together, i always have my 'right' ski in my right hand. i call it my 'right' ski cause it's marked 'right' so i can tell the difference). this may mean you could not be randomly dropping your skis, they might always fall on the same foot. and if you always ski on the same edge, you could be having a better edge between tune ups or when you sharpen your skis. your essentially wasting an edge if you don't switch skis.