Leave your wax thick every now and then and take a look at the wear patterns on your bottoms after your first run.
Its a great way to tell whether you are karvin', skarvin', or skiddin', whether or not you are pressuring your skis fore, aft or centered, how much edging you tend to use, etc. Usually you have to enlist the aid of a few weeks of cooperative small rocks to get the same info
Without fail, every time I look at the scratches on my bases, I wonder to myself why any sane person would spend tens of thousands of dollars and huge amounts of time just to have base scratches that run fore-aft, and not diagonally. Non-skiers would never understand.
Tom / PM
PS - BTW, if (as suggested) you don't scrape the wax, they will ski very strangely for the first few minutes. Usually, I can't even skate or get an edge when the wax is still thick.