Component Break In. Truth or Fantasy

Transducers, like cartridges and speakers, yeah, fo sure. Electronics, I dunno. I run tubes on everything so the devices that process the signal largely degrade from start, I suppose capacitors might have to "form" but the biggest issue is simply warm up- 45 minutes-- rather than break in. Then again, I haven't had a new component for a while. When I got my phono stage- an Allnic H3000, I definitely remember a break-in interval--that's been a while. 

I've had headphones that I bought that I was ready to return they sounded so bad; I contacted the manufacturer and they said they should have at least 150 or so hours burn in. So I put 'em on the back of a chair, played music through 'em without listening for a week or so, put 'em back on again, and they may as well have been different headphones. My experience with speakers is the same; I've had very high-end speakers that sounded like the woofers and tweeters had never met each other, out of the box. It was a happy marriage by a couple of weeks later. 

Planar headphones are kind of like electrostatic speakers. The diaphragm vibrates from the electromagnetic force that eventually creates sound. 
With that said, is a break in period of 150hrs unreasonable? To me it’s not. 

IMHO, most of the break-in is our ears and brain becoming accustomed to a new piece of equipment.  Clearly things that have moving parts are likely to change somewhat.  Having said that, it's a moot point as everything is going to get broken-in simply by using it?  Is it my ears or the equipment?  Chicken & Egg kind of question.  Cheers.

Break in 1000% fact,most notable on speakers/headphones,electronics to a lesser degree & cables almost never in my personal experience..
 Planar headphones might be the single greatest example of this fact..Every pair of HiFiMan I've ever owned(HE400i,Sundara,HE560V2 & now Ananda Nano)started out sounding like I was listening to a childs plastic toy drum set,absolutely zero definition,detail or naturalness,just thump thump thud..Slowly but surely you could hear things start to open up & advance towards the final,musical,wonderfully natural sound that were capable of..A pair of iBasso SR-1 with Bio-Cellulose drivers started out so dark & veiled it was like listening to a pair of speakers with blankets thrown over them(anyone remember the first generation Vienna Acoustics Haydn?),now sounding like the finest 300B Single Ended Tube amp driving Harbeth speakers..
 Most recently,my new ProAc Response D2D speakers..Started out about 6 weeks ago I thought I had made a huge & costly mistake.Bright,brittle treble,sloppy,one note bass,no imaging or staging..Now with about 500 hours on them the bass is tight & deep,the treble extended but smooth & imaging/staging the best I've ever owned..
That is NOT just the brain getting used to their sound..