I have a video of myself doing this drill. 2 shots to center mass target was about 7 yards out.
http://youtu.be/UsEtgG-Fx1A
I had a long sleeve pullover sweater on and the gun was in a kydex belt holster. I wore it the way I would have in the real world. Both shots were combat accurate, not 1" groups. Thry were slightly larger than a fist or more like a open hand. I have been shooting for just a year now. when that was taking about 10 months of pistol shooting. So I def think if your doing this drill not from concealment you can get off maybe 3 to 4 shots of.
I watch the Magpul guys do this drill and get of 4 shots in under 2 seconds with the gun covered. Thats were I want to get my skills to. Right now 2 shots in under 2 seconds with the gun concealed I will take that for now and be happy and build on it.