You can now fly the plane with the engine set slightly below the optimum setting for four or five flights and it will be completely broken in. I have found this method works well with the ABC type engines. The break-in for ringed piston engines is similar but you don't run as lean at first because the piston ring needs time to seat in the cylinder liner. In all cases, avoid dusty surroundings. I run my engines in on a test stand on grass for this reason.
Landings are mandatory.
God meant man to fly, he'd have given him more money. It's better to be down here wishing you were up there, than up there wishing you were down here. Want proof make it stop, then watch the pilot break into a sweat. Speed is life, altitude is life insurance. No one has ever collided with the sky.