Break in time for new engine

let me think what I did for the last 2 engine I did

let it ran 1/2 hour at 3000 rpm for the first one
change the oil and drove it like I stole it
this engine ran very well for almost 10 years
and I sold it to a friend

for the second one its a roller cam so no breaking
was needed for that parts so I let it ran at 1500 rpm
for 1/2 hours and ounce again I drove it like it was stole
still running this engine for the last 3 years