I don't it's a guess!!.
No this is just what I do, everyone has thier own opinion, years ago when machine tolerances and oils/components were not as good, it used to be very slowly for ten zillion miles etc, but the same procedure today will cause a smoky engine, and is not needed.
Saying that the last hire car I had FOUCS 1.4 was so gutless due to everyobne babying it, I thought a good thrash would help, the difference in 300 miles was amazing, don't think they liked 2000 miles in two weeks though!!
tabetha