I believe it has to do with the disc material, I had my RXT installed and drove about 100 miles then put about 45 passes on it. Its all good, 2000 miles I'll be ready for another one.lol
IMHO I would say 400-500 reasonably easy miles should do the trick it most cases. I took my car down local roads with plenty of lights and stop signs for 2 weeks after work and that really helped matter. Boring as all but the clutch broke in perfectly no chatter at all after 500 miles.