I was under the impression that the jacket would hold the spiral?Depends how you handle the cables when unplugging and whether the cable clamp (i.e. integrated into the plug) is holding onto the sleeve securely.
Some audiophiles can be a bit "ham-fisted" and even though they know NOT to pull on the actual cable they do so anyway and the cable could unravel.
The cable as finished by the manufacturer will not unravel because of the molded plugs at both ends.
Also - the cable clamps on the available plugs vary widely and so does their ability to clamp a cable successfully
I like the Silver plated copper line of Sonarquest plugs (Ebay) - the IEC plugs grip like a vice.
Regards - Steve