Lab and field tests have found "break in" to take thousands of miles but the bulk of it occurs in just a few K miles.
Experts agree that a more aggressive broken in engine will make max power sooner than one broken in using a less aggressive manner. Whether the max power would be the same or not had the engine been broken in less aggressively no one can say.
But experts also agree that an aggressively broken in engine will experience a fall off in max power sooner than an engine broken in less aggressively.
This is not say one minute the engine makes max power the next minute it is a dog. I would hazard a guess the drop off takes a good number of miles. A low miles car with an aggressively broken in engine might be just fine. It is with the 2nd or even 3rd owner the engine's power begins to fall off.
By not following the break in guidelines but instead being more aggressive with the break in there is the risk of ring/cylinder "damage" that could result in an increase in oil consumption. It could even affect the amount of compression one or more cylinders developed.
Even following factory break in guidelines oil consumption during break in (and after) can differ from engine to engine.
Based on my experience with both my 2018 Hellcat and my 2020 Scat Pack the "right" amount of oil in the engine has the oil level up above the max line by a fraction of an inch, maybe 1/8th of an inch. This after being serviced at the dealer. Different dealers, too. I've asked about the oil level being "high" on the dipstick and have been assured the right amount of oil has been added to the engine -- this after a proper drain procedure followed. The "problem" is the oil dipstick just does not reflect this. I bought an upgraded oil dipstick for my Hellcat which when combined with the proper dipstick tube -- which was on back order -- would have the dipstick agreeing with the actual and correct amount of oil in the engine. But I traded in the Hellcat before the oil dipstick tube was available.
For my Scat Pack, like I did for my Hellcat before it, I just note the oil level when I get the car back from being serviced -- I check it right in the service department check out line -- and note the level and it is above the max line by a fraction of an inch. So far I have not had to add oil between oil changes to the Scat Pack (nor the Hellcat before it) but if I do I will use the higher level of oil as received from the dealer as the level I will seek to match.