Driver breakin period, what’s the science?

In some speakers and electronics the difference in break in can be dramatic but in others there is only a slight change my hope is that the drivers are real good and the former will occur for you but what i can say is that letting your system warm up with background music for an hour or two will really help before you seriously listen every time you play your system.

I doubt there is very much to it. It is mostly your ears getting used to the new speaker. Yes, there may be some break in happening like anything else, but no where near as long as some suggest.

Are you using ported speakers? Is that how the spiders enter the enclosure? My cabinets are sealed enclosure.  HVAC

Relative output of your driver's did not change more than a fraction of a db after the first few hours. The crossover points may have changed a very small amount.

Back in the day, we broke in studio woofers with a Crown DC-300 input pad plugged into the wall. Played 60Hz for at least 24 hours before swapping. Never measured for any level difference, but sonically, un-buzzed woofers sounded flat and lifeless. Old woofers were sent back for reconing. Mid/Tweet drivers could be reconed on site. Techs used to hang shredded diaphragms on the wall marked with the band / musician who blew them.

Note that the above speakers were abused and suffered mechanical failure. 

To the long break-in crowd:
Do you log listening room parameters Temperature, Pressure, Humidity, Line Voltage? see  ieLogical WinterBlues
How accurate is your level control? [Have you ever verified it?]
Have you verified the amp is operating at EXACTLY the same BIAS point?

My 35 year old speakers break-in CONTINOUSLY due to the above. The CBLF is infallible and contributes not...

Psycho acoustics? After MC comments, this makes no sense.

Everything makes sense. You just have to look at it logically. A lot of people are psycho. Unable to distinguish fantasy from reality. Some of them hear sounds, don't know what they are. They are psycho-acoustic.