My brother is an automotive engineer & he says that most newer engines are put through a break in cycle at the factory... (he) worked on all of his test engines at Kettering University.
I just toured the Subaru plant in LaFayette and they don't "break in" engines, and I doubt that any other manufacturers do, either. The time and labor would be cost prohibitive.
The engine is started and run long enough for the ECU to go out of safe mode and begin running on sensor feedback, then the car is driven a hundred feet to a transmission testing and setting station and then to a final quality check station. The stations have rollers and the engine is revved up and down through the gears. Then the car gets a short drive over the bump section of a test track before being parked on the big lot. That is the extent of any Subaru factory break in.