The more you take care of them, the longer they will last. Keep your edges sharp and deburred and the ski will perform better. Wax often to protect your bases from oxidizing ("drying out"). You can get some good advice at www.tognar.com.
I touch up my edges and wax every Friday night. If you do it often enough, a quick deburr and wax can be done in about 15 minutes or one beer. Major repairs may take longer and up to an entire six pack.