I was going to go with 10 years. I mean, nobody cared about Madonna's "Ray Of Light" beyond 1999.

On the other hand, artists - like Dolly Parton - have made long careers out of songwriting that have carried them into their senior years, so it's a balance.

Clearly 99 years is absurd. Maybe 20 years is the balance to strike. Dolly would still be doing just fine with that term.