Do speaker cables need a burn in period?

Yes, a farting demon as it were, thus the analogy. 

Lets follow a moral compass and  try to respect your fellow audiogoners. Let's get back to the OP. I believe in Burn in. Tubes certainly burn in don't they. I have experienced that for sure. Wire or metal is the same.

The compass points at Kitty. 🐈💩

He is a habitual offender, and can expect to get as good as he gets. 

How is that for a bearing to the station, for a non-precision approach. 🐍💩🙀

"I believe in Burn in..…...Wire or metal is the same."

Come to think of it, how many of us have seen a metal burning (in, out, in the middle, wherever)?

I think that may point towards the answer.

If your cable does burn, you need to switch to some fuse thread for suggestions.

Dodging the question. Tubes change in sound while burning in? No?  Yes they do and like wire it burns in too.