Always a fun topic :) IMO, something happens, but it’s not a mechanical “hard data” point in the life of your loudspeaker. In my most recent experience, I’m lucky owner of a pair of Wharfedale Heritage 85 Lintons. They are a very interesting set of speakers - a big baffle warm sound with better technology that their’70s ancestors. They are not as transparent as many high end audiophile speakers now available, but the color they bring to almost every style of music is pleasant and controlled. Tough to beat at $1,200 delivered.
But, to the point of the thread, my Lintons have steadily improved in terms of our enjoyment over a month of ownership without any special break-in. Three things are involved. First, the gradual refinement of their location (their rear ported 8” woofer bass response is best at about 20 inches from the rear wall and their polite tweeters and 5” mid range need a little toe-in to help them keep up with the sub-tones. Second, we just “hear more” from them as we listen. Third, I took the time to flag a number of cuts with distinct well-recorded intros that I play about once week since we settled on a set up. The resolution is definitely better over time with these sweet mid-century modern mahogany finished throwbacks.
Enjoying music is the goal and, regardless of our collective understanding of the engineering involved, speaker performance is honestly subjective. We’re thrilled with our speaker choice simply because they are drawing us to listen more often.