Mids and Tweeters do break in quicker than woofers. I've heard it many many times.. Crossover parts however, take a VERY long time to break in.. a solid 3mo + for capacitors.
To properly break in a woofer you must play the speaker with program material which contains a fair amount of bass content (obviously) and after warming up the speakers play them a fairly high level for extended periods. Preferably when you go to work. The woofers should be ready in about 400-800 hrs.
After breaking in over 40-50 new pairs of speakers, including some DIY projects, this has been my experience..
I'm not kidding either..
Hope this helps.