there are examples of bows with crysals that have long lives when re tillered,, I have a black locust, crysal at the fade,, that was about 20 years ago,, it still has no set, and I shot it in many tournaments , I did it when I first braced the bow,, but as I evened the tiller,, it did not get any worse, and is still a bow today,,,, a friend of mine crysaled his first bow,, but evened the tiller ,, he is still shooting it after 2 years,,, I think it really depends on how bad they are and if the tiller has been corrected,,sometimes the damage is to sever or not enough wood left to correct the tiller,,