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
If someone does have noisy power putting in the conditioner will have an immediate impact.The noise floor will drop but doesn't mean that their won't be some other changes in sound as the unit breaks in.

As for expectation bias I suppose we all have it,but what do you call it when you get a new 'thing' and it's disappointing and doesn't meet expectations?I'm not able to deny to myself that the 'thing' I was so excited about acquiring sounds like shite.
+1 to what millercarbon said. 
 
-1 to what georghifi said.
Paul McGowan- president of PS Audio states that break in is real and varies widely in the amount of time it takes for audio equipment to reach maximum performance. His company makes both stereo components and power conditioners.

He has an extensive series of  You Tube videos on audio subjects. Each is short in duration and addresses one topic. Very helpful.
David Pritchard
If you suffer from expectation bias and tend to fool yourself, you should not be in this hobby, and I have some $5k cables you might be interested in buying.
"expectation bias"
One of the best statements to be said with new gear, and Ralph (Atmasphere) as far as I know was the first to use it here on Audiogon forums.