Mark Williams recommends panic stopping on a slippery surface at low speed to test brake bias. Will this replicate real conditions? Don't Know. What I do know is you don't want to panic stop one day and find out the rears skid instead of the fronts, don't ask how I know. Most drag cars will skid the fronts with no valve do to tire size bias. But if all 4 skid together or the front just slightly earlier it'll stop straight.
Doug