When I use to break-in a fresh motor there were two critical things. First, keep the motor RPM above 1500 RPM so that you have good oil pressure. Second, change the RPM every couple of minutes to make sure that the rings, etc. do not take a bad set. Also, make sure the motor runs for at least 15 minutes once it has been started.
I was taught to use a lot of high pressure lube designed for cam shaft break-in. By the time that the rings are seated, the cam shaft is also done. This was done either on a dyno or in the car. Next step was to take it to the track and race it.