along with rreaction time, is the "shootoff" performance level at the Steel Challenge. Bill Wilson once got them all down in 1.6 secs, or some such, but he never again came close to such a time, so the guys decided that that 'run" was a either a timer malfunction, or a combination of pure luck and having 'jumped" the starting beep(saving .20 second of reaction time, you see. The time would thus normally have been 1.8 secs
It most certainly IS possible to react, draw from a speed rig, and get off 5 shots, as you move the gun across a row of targets, in 1.8 secs. What's luck is hitting all of them, if they are only 10" wide and are at 7 yds' distance from you.
The reaction, draw and first hitt can be done in as little as .55 second, given a "hand hover' start-posiiton, or as little as .65 second, starting hands at sides. That leaves 1.11-1.25 seconds in which to fire 4 more shots, which can easily be done, (if no hitting, of other targets is required of all such shots). 
It most certainly IS possible to react, draw from a speed rig, and get off 5 shots, as you move the gun across a row of targets, in 1.8 secs. What's luck is hitting all of them, if they are only 10" wide and are at 7 yds' distance from you.