OK I stand corrected for WC racers.
But is even a 'real' race boot from the factory not a starting point, a blank to mold to the skier? Every skier has some differences in anatomy.
What do you do with a skier, even an expert or good club racer, who has limited range of ankle flexion? Or some one with a long femur? So that when they flex/extend in a std boot their COM shifts to the back seat
What do compentent coaches & intructors do?
I have limited dorsiflexion. I set up my own boots, a friend builds my footbeds. I have eyes on my skiing. I'm also fairly self-aware of what my skis are doing on the snow.
For clients, i look at their boot set up, alignment, etc..., if there's an apparent problem, then refer them to a couple of people i trust, and communicate with them what I've seen in their sking to start the 'sorting out gear' process.
If i have time, I'll work on their boots myself.