As I've said before, I prefer premium plastic discs that don't wear in for a very long time, if ever (Champion, Star, Lucid/Opto); compared to plastics that wear in fairly quickly, such as most baseline plastics (DX, Prime, etc.). So my discs don't change their flights for a long, long time.
As an example, I still have the same Champion Panther that I put in my bag over three years ago, a disc I have thrown into trees, into the ground on spike hyzers and rollers, and used regularly at least five times a week... and it has not changed its flight pattern at all. By the time it does, I'll probably be too old and physically unable to throw discs anymore.
Of discs that have changed on me, most were already understable and have become too flippy to be of use. I have given away more discs than I have sold, mostly to young people to get them interested in DG. Others, I can still use for practice on the range.