I attended the revolver roundup last fall and watched DB run through this exercise. He did it well under a second, which I believe was a first for him, and as anyone who shoots competition knows, once you break the psychological barrier it gets easier on to repeat on demand. He and Wayne emphasize 2 things: not shooting too fast, and being sure of your hits. Maybe that should be in the reverse order.
With a 5 shot .38, nothing short of a perfect head shot is an (almost) guaranteed instant stop. Better to take another 0.1 seconds and be sure, than launch a glancing hit the have to follow up. For a close range torso shot, I agree- send ASAP and repeat as needed.
The snub is a “one robber” gun so you don’t have any rounds to spare.