Re: Fly line life expectency.
Pull out an old (way old) line. Lay it out. Inspect it. Clean it. Inspect it. Dress it. Inspect it. Spool it. Inspect it. Fish it. Inspect it. That's the only way to know for sure. Oh, did I mention that you should really inspect it? As long as it hasn't cracked or otherwise degraded, it's a fishable line.
I've been through that a few times. Finding out whether or not an old, forgotten line works is a true win-win situation. Even if it doesn't work well for you, it doesn't matter. You still get to fish. And we all know the worst day fishing is better than the best day working.
frus·tra·tion (frəs-ˈtrā-shən) n. Watching a nine year old with a cane pole and a tin can of worms catch his limit while you get skunked.