Tangential anecdote - In bootcamp, our drill instructors were famous for giving us a countdown and then counting us down along the lines of "You have 10 seconds, 10, 9, 7, 3, 2, 1, you're done!" In addition to skipping numbers, the "3, 2, 1" portion was said as quickly as they could manage. I think we only ever got about 50-75% of any supposed allotment of time. To this day, I still can't hear a countdown without wondering what numbers will be skipped, and of course, I expect "3, 2, 1" to only take up about a second and a half.