If the loudspeaker is not a crossover-less wide-band single driver design, the burn-in process is a roller coaster since each driver breaks in differently. A woofer, midrange and tweeter are physically vastly different. And as they break-in coherence and integration WILL vary widely.
We break-in speakers for a week at the factory LOUD (at nights) 24/7. That's equivalent to a year's break-in playing them 3 hours a night after you take them home (do the math). Hence, we confidently tell our customers that the speakers will only require minimal break-in after you take them home. But they will continue to improve for the next couple of years.