Never heard it put like that before.....I like it (and may steal it, by the way)!

In regard to you question(s). I feel that you never stop improving. However, the learning curve becomes quite flat at different points for different people, which effectively puts a "cap" on just how good you can become. If I were to practice 8 hours a day, I would never be able to be as good as Chip or "insert your favorite pilot here", but my abilities would greatly improve. Like the others have said, you do need to push yourself. If you are worried about tearing up your pretty plane....get an ugly one! Get a profile or a cheapy from a swap meet and fly the heck out of it.

Mike