In the conditions I usually ski I am probably incredibly negligent by New England standards. My everyday skis usually go about 20 days between tuneups. The 1986-vintage Rossi 3G's I used Saturday at Baldy probably hadn't been skied on for 3-4 years. I did test the bindings in the front yard and threw an extra pair of old skis in the car just in case. They worked just fine in the ideal spring conditions.
A few times I have gone from ski hill to airport, bagged the skis, flown home and put the bag in the garage, only to notice considerable rust when I next used them.
Marc is correct. The rust comes off after one run. But I do now pay more attention to wiping skis dry, particularly at/near the end of the season.