@JiggaTheSunGod Judging by the physical and mental state of the average Celestial Dragon, the amount of Conqueror's Haki needed to knock one of them unconscious is likely just one-tenth—or perhaps even one-hundredth—of the amount required to knock out the Marine soldier I mentioned earlier.
@JiggaTheSunGod Their Conqueror's Haki is so immensely powerful that even the slightest leakage can cause surrounding subordinates to lose consciousness. Consequently, unless faced with a dire, unavoidable situation, the admirals will not employ Conqueror's Haki.