I have an old beat up very overstable (was) Tracer. I've had it for 17 years. I swear this disc has turned understable. Do overstable discs turn understable when beat up? If so, is it all overstable discs or just some? Or am I just crazy!?
A disc should be used for whatever it can do well, even if it was once stable but ain't no more.
Way back in the day, before the advent of candy plastic ( so like 6 or 7 years ago), drivers changed more readily than they do now. At one time the best forehand disc on the market (imho) was the X-Clone. Within 6 months an X-Clone could go from fresh to severely beat up (from overstable as heck to flippy). My drivers were X-Clones. The only drivers in my bag were X-Clones. I carried 13 of them which ran the whole gamut of stability.
So my understable drivers were overstable when they were molded. I never thought I was violating the sanctity of the disc to keep using it as it changed flight patterns. Once you find a disc which fits in the hand well and flies well at the speed you throw, you want that disc in every (usable) stability variation.
It is the same rule in Mids. I carry 3 Buzzzes including one really best up.
With candy drivers the only reason not to break an overstable driver down to an understable driver is due to the time delay it would take.