I just bought a new pair of Salomon trail runners today, and along with them a new pair of green Superfeet. My old Salomon trail runners are just over a year old, but they, along with the old Superfeet, have seen a lot of action in that span. Seeing as these insoles are so expensive, I wondered if I should have just saved myself the $ and reused the old ones. But I didn't know if Superfeet also have a certain period of use before they are no longer worth having.