The only time I do that drill is if an FAA inspector is in the cockpit. I'm a firm believer in at least five seconds of consciousness for me to get my mask on between at FL260 and FL410! Experts have said that even at FL410, the average reasonable healthy person would sustain at least 15 seconds of useful consciousness.
This old regulation has been on the books since the beginning of time; there to protect the worst of the chain smoking nicotine and caffeine addicted pilots, flight engineers, navigators and radio operators. In the old days the cockpit was a smoking lounge, even stews would come up for a cigarette break.