This is where the turnover, or resting processes while remaining elongated comes into play. During the turnover (rest) phases, the tissues are more willing to comply with the elongation. As
@MickeyDeese pointed out the soft tissue remodeling in his early post, it's about straining the tissues, stressing them, then allowing them to heal over time as you place them under the long hours of traction remodeling influence, either through hanging or through stretcher/extender. Those who gone through so many years of lengthening for a certain gain of length, they break, and come back. It can be a year, five years, or even ten years. The body can be and will be able to change constantly, as long as you give the body enough time to adopt the changes to prevent irregular anomalies where it believes it can't support the new addition properly.