I am a wax tech. If you want to know what to run for a certain temp, go to www.swixsport.com and then proceed to their wax wiz page, type in conditions and it will tell you what wax to use.
My daughters race, and I service a lot of racers who depend on me to pick up time. If you are looking for better performance, you need to do a good amount of bench work to build up and season the base (see my thread on pre-season ski care posted on NS).
If you are one who doesn't like to wax to much, then wax your three times a year with a wax with a temp range of no higher than about 16 f. It will last longer. If you screw up with choosing the wrong wax temp for conditions, it is best to miss by having a colder condition wax on a warm day. If it is 32 and you have 20 degree wax on, you'll still have decent skis, but if it is the opposit and you have 32 degree wax on a 20 degree day, your skis will be sticky. Next is that temp ranges are influenced by hardness of the wax, colder range, harder wax. Warm weather wax is soft and not very durable. In the summer at our Hood store I recomend using a 10-18 F wax and people always freak becuase it's 60 on hill. If they looked at the box and chose their wax for a 60 degree day with that dirty sharp snow, they might get one or two runs before it's off the ski. The harder wax last thru the day.
So, lazy waxers.... wax once a month with a medium cold weather wax. Wax nuts, read the labels and wax to conditions every night before skiing, and if your in the middle, go with the low temp for the week and wax to that condition every week.
BTW... I swear by Swix brand wax if that is what you want to know.
