In my testing on the Nightshades about ~90% of the break-in occurs when I test them on the bench before shipping for a few minutes. Several more weeks of play may result in ~10% more break-in. Some woofers will vary a bit... but most of the break-in is going to happen pretty quickly.
my L5 got way louder after about 6 hours of playtime at moderate levels,same with all others.biggest thing i noticed on all my new subs is voltage drop while breaking them in.after they are loose,the voltage drop goes away.atleast thats my experience.