Driver breakin period, what’s the science?

So have these new speakers and been told they need a hundred hours to be broken in, and then sound will improve.

What’s going on as break in occurs?  More important for tweet, mid or bass?  
My initial listening has simple vocals/music passages sounding very good, and more complex and very layered sections that may have potential to improve.  
Heavy, high excursion butyl rubber surrounds, and stiff spiders (springs), they take a while to loosen up. To sound clean and go DEEP, 50-100 hours (over night on a tone generator)

I have GR servos. LOL took a couple of hours to hear them and all night to loosen up enough to hear well.. Weirdest thing I ever seen.. Like magic. I though they were broke. They were moving but, no sound. I think it had to do with the correction side of the driver, and the servo amps.

Lighter foams and springs, less time. 20-50 hours..

I’ve seen teflons caps in XO take a 200-300 hours too. The drivers were broke in long before the caps were.. Sound wonkie as all get out.. for a while.. Ear bleeding stuff, mercy.

Spiders a few minutes, surrounds  few hours. I doubt it's anything audible. Mostly you getting used to them, keep listening and forget about break-in.
the better the speaker and the more resolving the system is, the more this can be noticed, happens over the first 100 hrs at least... for mine, changes were noticeable up for 300-400 hrs...

this is significant... those who say no just don’t know...

One of my business partners would beg to differ having done extensive work on cone materials and cone breakup which required extensive testing of drivers to determine where parameters stabilized including high speed surface imaging and laser interferometry.

So have these new speakers and been told they need a hundred hours to be broken in, and then sound will improve.

This statement above is total crap. It does not take 100 hours to "sound good". There will be subtle changes after hours of reasonable volume. No magical major improvements after that. The only thing that happens by 100 hour is you got used to them.

w.r.t. Capacitors, electrolytics if they have been sitting can have a parameter change over a period of time, mainly in DC parameters, but you don't see those too much in high end speakers. Film capacitors are very stable is why they are used. There are people who have equipment and can test these things to significant accuracy. They are not the people making the claims. We can't measure how humans will perceive change, but we can measure if there is change.

A guy named Mike Samra, red sock green sock guy. Told me that teflon caps break in because of the DC, yet the speaker's VC would fry with it.. 

If it takes DC to break in a teflon cap, I still haven't figured how they breakin, in an XO, but they do. They sound bad (TRT) expensive caps too. Very harsh, highs will blister your ears, mids are veiled. They didn't effect the bass because there is no caps in a 6db first order low pass. But a bit boated because everything else was all out of whack and very thin. Thank goodness for Lpads and tone control.. It took 200 hours before my tone controls were back to flat, and Lpads at 11-12:00.

4 pairs all the same...  Years on a center speaker, because I don't use surround.. That one really cracked me up.. Any one need a LCR VMPS neo 8 planar center speaker. Just broke in after 13 years NOW... LOL

Some stuff does take a LOT of time.. just sayin'

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. The l-pads and tone controls were not doing what you think they were.