I still use it, so I don't think I'm wasting my time. When I'm feeling particularly frugal I recycle flies that I've retired because they've come apart (after being chewed by lots of fish obviously ). When I strip the remaining materials down to the glued bits I still find there's a lot of strength left and the glue has to be chipped off. I couldn't tell you the age or exposure (to saltwater) of these flies though - with bonefish I tend to leave the same fly on until it gets wrecked - this could happen in 1 day or a couple of days (or it could go back in the box if it's been rejected and I have changed pattern).
Cheers, James