I have always waxed my strings and on most of my bows I also lightly wax my center servings. The only one that I don't is my Ravin on the center serving. I do not wax every ten to 20 shots like I see some advocating on the forums though. I wax when they start looking a tad fuzzy and dried out.
Been using the Scorpion Venom Polymetric on my vertical bows for about 9 years now (two Elite Judges and one DXT). But been using wax on my other crossbow and rail. I was sure glad to see Ravin insist on something like Scorpion Venom!