One of the main reasons why I change strings is when they lose their tone. As part of that tone loss my observations over many decades is that the intonation can suffer as well and therefore the bridge will need adjustment for intonation . As a result I stay away from old stretched out used strings, new old stock is fine in my opinion . I used the Pyramids flats in the 70s . I also have some new Pyramids some of which were made for me in custom gauge orders . The new ones are a little different in feel and from a spectral aspect in sound .
