My hunch is that the practices of elite-level ski racers are to blame for compounding the ski-tuning myths that wax should be allowed to cool before scraping, and that extensive scraping and brushing is necessary before skiing.
The very best racers (e.g., about a third of our league) have separate pairs of train and race skis for each event, with the race skis used only for their race runs. Therefore, the race skis have not been skied on before the race run, and extensive scraping and brushing (often with a drill-powered roto brush) is necessary to remove all the wax that is still on (as opposed to in) the base, as well as open up the structure of the base. Letting the wax cool is also beneficial, since as soon as the iron leaves the ski the wax starts to be pushed up *out* of the base (NOT absorbed *into* the base). Therefore, if you scrape while the wax is still warm, and the goal is to remove as much surface wax as possible, you will have to scrape once again as the base cools down and forces more wax out of the ski base.
The implications for anyone other than racers with two pairs of skis for each event are quite clear: immediately after you wax, aggressively scrape the extreme tips and tails (where the wax tends not to come off from skiing), then just smooth out the area underneath the foot a bit. Two caveats: more aggressively scraping will be necessary if:
- you ski on something other than eastern hardpack (luck you);
- you're really lightweight (e.g., my girlfriend, whose skis would still retain wax if I scraped them as minimally as my own); and/or,
- you're a female racer, i.e., running early by which time all the wax might not be gone. (Other racers might need to do a little bit of scraping and brushing before your race run, but almost all the wax will already be gone from the surface.)
Of course, by not scraping aggressively before skiing you will indeed be slower for the first couple runs, but if anything you'll be faster later in the day since your ski will still have a bit more wax. Anything else is just a myth. (At a coaching clinic, when I pointed out to a representative from Reliable Racing Supply how extensive wax removal was superfluous for late-running guys lacking two pairs of skis, he provided a highly unconvincing response about how horrible skating to a distant lift might be early in the morning with a thick coat of wax.)