Perhaps one useful outcome of that experiment is that testing alone doesn't prevent a workplace from becoming a super spreader site.

Yup, which lead to early treatment. Most people start treatment when the illness has progressed far. Hospitals generally withhold treatment to see if patients will recover by themselves because they can't risk "waste" of medicine and filling up hospital beds. So most people are sent home unless it's really bad. Trump started getting treatment from the very moment he tested positive.