About 1 in 10 of my jobs pre-stretched snap on a mishit. However, the ones that last, play well for at least a week. The jobs not pre-stretched completely lost there control after about 3 hours of play. Made me wonder, what's the good of a long lasting poly if it doesn't play well? Was it the string? Those were with Gosen Polylon SP 17.... I am thinking of trying others...any suggestions?