I keep my edges sharp, and I've never planed a sidewall. A bit of plastic in the file teeth has been no problem. I sharpen just enough to remove the minimum amount of steel to get a sharp edge. I've never ended the life of a ski by filing the edges so much that the edge is disappearing. Some skiers with many more ski days than I put in do consume skis that way.
I'm a western skier, and I like 3° sides. On powder skis, less acute angles means less of a divot is taken out when a rock is hit, so those get 2°. 1° base on the powder skis and 0.7° base on the carvers. I started at 1° feathered to 0.7° for the first foot at the tip and last half-foot on the tail, but now just stay at 0.7° all the way. Just a bit grabby until I get the feel for them, then nice.
I'm a western skier, and I like 3° sides. On powder skis, less acute angles means less of a divot is taken out when a rock is hit, so those get 2°. 1° base on the powder skis and 0.7° base on the carvers. I started at 1° feathered to 0.7° for the first foot at the tip and last half-foot on the tail, but now just stay at 0.7° all the way. Just a bit grabby until I get the feel for them, then nice.