If something is going to change its characteristics through this kind of "break in" procedure then it isn't suitable as any kind of long term use. The idea behind designing a transducer is that it is reproducible, reliable, and predictable. If the material changes properties durng use, then it is not very desirable.
People who think that headphones or speakers need a break in are fooling themselves. They need to ask themselves this question: If the transducers change so much during break in, how do they magically stop changing after this alleged break in period?
Another: If they change properties so drastically during break in, how long until they change beyond being "good" again or utterly fail from the same change in characteristics?
So golden eared people, how do you know your "break in" is finished? How do you know that it isn't continuing? Where are the measurements? I know, Stereophile says it must be so and you just spent $400 on green pens for the edges of your CDs, $10,000 LED illuminated speaker cables, and $50,000 per channel for your single ended 300B triode 1 watt amps, so you know you are right without having to prove it.
What harm is there in believing this BS? Well if the effect of believing completely baseless claims, without any reason to do so, is just to belong to an exclusive club, then no harm. But the effect in believing in some woowoo in one area of life inevitably is to believe in woowoo when making other important decisions. Things like that immunization is the cause of autism, there is magic man somewhere controlling your life, crystals swung around your body can detect disease, and pure water can cure anything, are just some examples of this problem.
Believers believe. Scientists don't believe, they act according to real measurable evidence. Actually a scientist is happy to be proven wrong. If isn't possible to measure or repeatedly quantify it, it doesn't exist.