Pat, I've always shot with a large group of guys as you know, and one or two of them would sometimes have a new string and needed a string nock. Before I placed a nock on their string, I always, out of habit, depressed the bow over my lap to stretch their string out. Well, the bottom would drop out of their brace height. That was never the case with my strings. In those days we all used the Dacron strings. Only difference in our strings was the manner of twist.
Even here on the boards, when you start talking about Dacron strings, some guys are very satisfied with this type of material, and others hate the stretchiness of the material. Perhaps the manner of twist has some bearing on that....Art