[Mister Moose]

My Model A engine rebuilder instructed me to run for short periods of 10 minutes and then a cool down. The explanation was the rope rear seal would burn if run for too long, that it needed to seat from wear over a longer period of time. If the engine was run too long the rear seal would carbonize from the frictional heat before the seal was worn in.

*Edit I was also instructed to use mineral oil for the first 500 miles for better seating, AD oils were too slick.

Aircraft cylinders have the diamond cross hatch pattern you describe. On brand new engines (I flew a lot of them) I was instructed by Continental to run at no less than 75% or even 80% for the first 10 hours. The explanation was the higher power settings gave higher cylinder pressures, and this would expand the rings to seat effectively. If the engine was "babied" when new, the cylinder walls would glaze and the rings would never seat. I'd expect an aircraft engine would be machined to state of the art. The engine was shipped with mineral oil, which would stay in for the first 50 hours, and then go to synthetic.

Outboard engines (2 cycle) were different still. OMC and Mercury instructed to run below half power for the first several hours, gradually increasing the power thereafter, and not to run at a constant power setting.

Obviously different machining methods and different materials lead to different instructions.