What is the best way to break in a new engine with steel cylinders. I always thought you wanted to baby steel cylinders by running at a lower rpm as much as you could, and run chrome cylinders as hard as you could. Continental motors service bulletin m89-7r1 states in part;

Level flight cruise should be at 75% power with best power or richer mixture for the first hour of operation. The second hour power settings should alternate between 65% and 75% power with the appropriate best power mixture settings.

But it does not say anything about how to operate after the second hour. Does this mean that it doesn't matter? What say you engine overhaulers???