Hi
I would say that it is more the easyness with which the kite will get ripped again
I had one kite, still looked good, but the price of the repairs were beginning to be close to the price I bought it (2nd hand)
and also I didn't trust it anymore because the last time it just rip on a small crash.
Even if good looking, it was too much used, too much sun.
So yes, until you don't trust it anymore or the price of repairs are just too much

Matt