on the other hand, i worked a fly shop through college and am still using 4x and 5x leaders from 14 years ago that i purchased and loaded up on when i had the discount of a lifetime. i have notice no difference in their strength, durability, elasticity, etc. i have kept them away from light and in a cool dry place. no problems.
how long is that leader sitting in the factory or retail stores inventory before they stock their shelves?
in conclusion...if i was going for a species i don't usually target i would have new leaders in my arsenal

peace,
scott