Why no “Break in” period?


If people say there’s a break in period for everything from Amps to cartridges to cables to basically everything... why is it with new power conditioners that people say they immediately notice “the floor drop away” etc.  Why no break in on that?

I’m not trying to be snarky - I’m genuinely asking.
tochsii
There is also this little part of the story that seems to be skimmed over.

In the end we invariably find a measurement that matches what the ear hears and it becomes very obvious to everybody.

So they don't  stop with well some think they hear something and some don't  they investigate what's  going  on.  
prof,
" Do you get this nuance...yet? Do you think you’d be able to actually depict my argument without strawmanning?"

Me,
Again, try to be honest with yourself. You believe that measurements trump personal experience & there is nothing that can be said to persuade you of this until science catches up to our hobby. As a consequence of this opinion, what you believe to be "nuance" doesn't exist.

I'm really not "strawmanning" you... it's just that on this footing (measurements trump personal experience & there is nothing that can be said to persuade you of this until science catches up to our hobby), your argument simply can not be argued.   
All items require a specific breakin period.i have been into audio 40+ years 
and owned a audio store for almost a decade dielectrics ,as well as new metals expand and contract untill threal ey temper or settle in ,even upgrading connectors from say a brass to a good copper detail and refinements improves over time,the crap thst your esr just gets used to it is BS li have done many a blind test .believe what you will ,I have the best instruments In the  world 
the ear to determine what is real and what is an illusion!!
Re speakers: not to enflame anybody, but I believe it's the spiders more than the drivers  that need breaking in.

Re electronics: I can understand certain components like capacitors benefiting slightly from break in, but I have never experienced any clear improvement over time with any electronics. But I'll cheerfully concede that it's possible. 
Exactly, TIM was the same situation. We all heard something wrong then they finally figured out what it was and how to measure it. But this is not what we are talking about here. We are talking about differences people hear when there is nothing wrong. We are not talking about what the ear hears. We are talking about how our central nervous systems interpret what the ear is hearing and that is a far more complicated and plastic issue and it seems in this forum modulated by ego. Many of the explanations are being devised by people who have no idea what they are dealing with or talking about with an unfortunately high level of arrogance. What is even more interesting is that the people who are closest to the truth are attacked the hardest. 
If people do not want to understand how their brains can trick them and spend their money on worthless garbage that is their prerogative. Do not think this is the search for the truth. It is more or less the re enforcement of mythology. 
Geoffkait, Einstein was a "Newbie" when he came up with the theory of relativity.