During the past training year my coach and I have structured the strength program into cycles; usually 4-6 weeks in length these cycles allow the body be shocked and then adapt to the specific loads placed on it through the activities. Each new cycle builds on previous gains, allowing for variations and new exercises.
Currently I am finishing the last cycle, in preparation for the snow to fly. I find that strength allows me to perform my sport specific activities more powerfully and with less overall strain; meaning an ability to continue longer at a set power output. Moreover, it aids in injury prevention.
Strength is a great complement to any workout regime, but a novice must be instructed and helped at first by a fitness professional or coach. Safety and proper technique are paramount.
Keep those skis Straight.