HF usually only for days where snow is of a higher water content....other than that it's a waste of $$$.
To add, the HF benefit is limited to a short distance (something like less than 400m?) so not much use if using the same ski to inspect, do some free skiing warm-up, etc. and then race on.
Reason why the WC racers have a dedicated race ski prepped at the top that they don't even stand on until they are ready to get into the starting gate.
Further, the benefit of HF wax is also greatly decreased when the speed of the event decreases. E.g. more benefit for DH/SG than SL.
I thought it the need to clean HF out by healthy amount of base hot scrapes was that the flouro gums up the base and makes it more difficult for HC base wax to penetrate. Since you want to build up a good HC base than then add flouro, important to scrape the flouro out.
Flourowax IS more durable to abrasion than standard HC wax, so that's a benefit!