If the wire is properly captive under the screw head, then IMHO it doesn't matter if the wire is wrapped clockwise or counter-clockwise.
This however is a matter of good practise: when you go clockwise, the wire pulls into the screw, and when you go counter-clockwise the wire gets pulled out of the screw. It is _harder_ to install the wire properly when your hook goes counter-clockwise.
Consider a wire that 'loops' around a screw, coming from somewhere, going 3/4 around the screw, and then continuing to another location. You can no longer define clockwise or counter-clockwise for this wire, but it can still be properly seated under the screw head.
-Jon
