The days of required break in periods are pretty much done. The accuracy & precision of today's engineering, especially in a Toyota, is far beyond that.
Oil is distributed throughout the motor in less than 30 seconds, so I don't think that has anything to do with it.
What used to happen is all metal parts in a motor had sharp edges from manufacturing. Those sharp edges needed to be worn off slowly so that they would not scrape craters in other metal parts. Old organic head & other gaskets took time to cure before you would want to put them to the test. No machined parts were perfect back then, just like brake pads, the piston rings wore to conform with the cylinder walls.
Now days, all parts are machined to very precise standards, there is no left over metal or imperfections. Gaskets are either cylicone or metalic, so they work fine right away. In short, a break in period is not necessary any more. Its more of a precaution that anything.