I have never heard of that either.

If the serving is tight like it should be then the wax isn't going to penetrate into the individual strands any how and the wax that was on the strands when the string was made isn't going to get worn away like it does on the exposed strands.

So, no I do not wax my serving arond the cams. I do use a little wax on the center serving though just becasue it takes a lot of handling and wear.