I'll try to give a serious response. From my experience, almost everything I have purchased changes at least a little after some operating time. Some things take much longer than others. My Denafrips Terminator DAC, for example, and the Nord Hypex amps I used to own, seemed to take a very long time (many hundreds of hours) before they sounded their best. Other products change very little.
My personal theory is that it is primary dielectrics that are changing with use. Capacitors and dielectrics used for wires tend to have the biggest change.
Mechanical devices (such as speakers) also have some break-in, but this doesn't seem to take that long - maybe a few hours. But the capacitors and wires used in the speaker can take considerably longer to reach the point they are no longer changing.
My personal theory is that it is primary dielectrics that are changing with use. Capacitors and dielectrics used for wires tend to have the biggest change.
Mechanical devices (such as speakers) also have some break-in, but this doesn't seem to take that long - maybe a few hours. But the capacitors and wires used in the speaker can take considerably longer to reach the point they are no longer changing.