White Frost was one of my first Mac eyeshadows from about a year ago, and about 50% pan is showing... I'm not really even sure how. However, I bought Folie for my brows in June 2009 and it looks as though I've barely made a dent... obviously I do my brows every day, with occasional touch ups later in the day.
I think it depends on the texture somewhat, to be honest. The softer textures tend to fly up into the air, kind of wasting some product