Oops, I thought I was being civil
Yeah, "break in" and "run in" are the same thing. I usually like to use "run in" but if someone uses the other term in a question I'll generally go along with it so there's no confusion.
Yes, higher oil content is preferable during run in/break in
because this means that for the same amount of running more oil passes through the engine. But to try to answer as best I can I'll give a real life example.
I've got an ST G51 which (for reasons completely unknown to me) is by far the most economical engine I've ever had. It runs for 6 minutes on a 3 ounce tank using 20% all castor and zero nitro. Now this should have been more than enough oil but it continually overheated and gave erratic runs. Then the light bulb went off over my head. With 20% oil, that tank held 0.6 ounces of oil which had to last for 6 minutes. In other words, only 0.1 ounces of oil was going through the engine every minute.
It was plain that 0.1 ounces/minute wasn't enough so what to do? First there's the obvious...add oil
which I did (to 25%) and that transformed the engine. Now there was something like 0.125 ounces/minute flowing through it. *
But there was another way and that would have been to up the nitro content (from zero to whatever) and increase the fuel consumption. Let's say that now it could only fly for 5 minutes on that same tank with that same 0.6 ounces of oil so it's using oil faster...at about 0.12 ounces/minute or almost the same as what happened by adding oil.
So what I was saying in that quote wasn't that low amounts of oil could be good but that by using a higher nitro content could make the engine believe there was more oil in the fuel.
* I can't help myself when it comes to things like this
At the 8000 ground revs (4 stroking) that I was running this engine it means that every rev there was 0.0000156 ounces of oil going through it (or in real measurements
0.00046 cc). If my maths are right then this is the same as a ball of oil 1mm across going into the engine every rev. And seeing the engine doesn't fill up with oil it also means a ball 1mm across comes out of the exhaust every cycle (one mm is about 1/25th of an inch). Imagine how much heat this can take out of the engine