Reply To: U.S. Question, is interval for 50yd repeat length for 500 free too long? Home › Forums › General USRPT Topics › U.S. Question, is interval for 50yd repeat length for 500 free too long? › Reply To: U.S. Question, is interval for 50yd repeat length for 500 free too long? March 4, 2015 at 8:06 pm #2372 AnonymousInactive 4-6 times race distance? For many that is a GUARANTEED best time, as opposed to being predictive.