35+ years ago grandpa bought a new case tractor, some thing he did not do often but he needed it.
The darn thing used oil Grandpa was not happy. Dealer kept saying give it time to seat in. Well first season it did not change a bit.
The next year Grandpa hooked it to a 3 blade plow set the blades as deep as they would go he started out in a low gear then shifted up till the engine was pegged on temp and the exhaust pipe was glowing like a Hd in summer.
After that day the tractor never used a drop of oil out side normal use again.
He figured he would fix it or blow it up .(Warning do not hook your HD to a plow and try this)
Todays engines are a bit different I have rarely seen one that did not seat in.
I have always broken mine in by riding them very the speed and never had any problems with any of them.
I have never broken in a new car any different than I drive it everday had no problem with them either