In recent DSF Instructor class I took about 2 weeks ago, we didn’t time ourselves but I gotta think my reload is sub 1 second. Obviously that’s in a range environment, my garments have been cleared and conditions are optimal. Also I keep my extra mag in a mag carrier, not in a pocket.
Honestly (again without a timer) I believe 1 second is totally obtainable. Then again maybe because we don’t use timers in DSF, my perception of time may be skewed.
3 seconds is a lifetime in a gun fight.