a string will never stop stretching but depending on the string it could take anywhere from 50 to 200 shots to settle and initially stretch out. if installed with the right amount of twist it won't take long. after that it's very gradual and practically unnoticed by many. after it settles sometimes the peep rotates to the side when at rest. some rotate the D-loop to "train" the peep. i like to instead add another twist and/or remove and rotate the whole string so the peep is at it's natural point of rest. i'm just picky and have the resources to do the stuff myself. some replace a string once a year, but i don't. after a year of shooting you might need to add some twists to get it back in tune or to spec. also you may notice your peep will come around right but you can actually twist it and change its rotation a little with your fingers. also it may not maintain its position from rest to full draw and instead rotate into place once coming to full draw. all this is fine and you don't NEED to replace it as long as you can maintain consistent accuracy and make your shots count.