Do speaker cables need a burn in period?

That would be quite an average listener. With Purist Audio cables that I have I heard no or almost no difference after 300 hours, interconnects or speaker cables. In higher resolution system - maybe. Jim Aud of Purist says 300 hours for his better cables, and I agree.

I’m not sure I have heard burn in benefits from very inexpensive cables either...

To be honest I don’t listen for cable burn in, contact enhancer burn in, system burn in CD results. Is that wrong?

You know !

Burn-in and directionality are untested and unproven concepts that contradict the engineering and scientific concepts related to sound. Many people believe in this nonetheless, perhaps because they experienced this. But even here, how do you know if you just get used to the sound of the cables, so they sound better? It’s a subjective thing by definition. 

I did did my own test, using Nordost Quattro Fil XLR cable’s. I had two identical interconnects, and I put one aside and used the other for six months. Then I compared them and didn’t hear any difference.