Do speaker cables need a burn in period?

Like I said before, just a quick look around would dispel any questions:
https://forum.audiogon.com/search/index?utf8=%E2%9C%93&query=cable+burn+in+services

There's more as well using other search parameters.

All the best,
Nonoise

Cable burn in service "for free".  Oh wait it doesn't exist.  Its interesting how one is willing to disprove oneself.  

Nice try.

Free burn in on all cables on their custom cable burn in unit (and they are not $7,000 cables):    https://www.avantiaudio.com/cable-conditioning.html

Cable loaner program (prices start at $700). Cables are burned-in before shipping:    https://www.taralabs.com/cable-loaners

Only charges $10 using off the shelf device (one built for MFG would be much less):   https://completecableconcepts.com/collections/cable-conditioning

That was just a quick search. It is a marketing decision, and it could be done very cheaply in production.

Economics in Eight Words: There ain't no such thing as free lunch.