It is actually serious business for these folks. Obviously cables don't have a break in and, for that matter, neither do speakers. What breaks in is our familiarity with a change in sound. After 100 hours we will prefer what we have to what we had in the past because of familiarity - just part of perceptual hearing. That reduces returns. Hopefully, the cable won't produce a change in sound but the psychology of familiarity still plays a roll.