That last point is extremely significant and too often overlooked. There's a graphic, painful video on YouTube discussing how it is generally serious error -- sometimes fatal -- trying to "outdraw" on someone who already has gun in hand. Two videos are used to demonstrate: the first is security footage of an officer on patrol attempting to fend off and draw on a suspect already holding; the officer is killed. The second shows an off-duty officer in a similar situation waiting until the perp's distracted, then turning the tables.Lots of dead mirrors and television sets have resulted from fast draw practice. Start with smooth, and speed will come. You'll never outdraw a pistol already pointed at you . . .
Situations vary and are sometimes unique, but the object lesson in these two instances is stark.
For anyone interested in viewing the video comparison, go to YouTube and search "don't draw on a drawn gun". Again, the example of when not to immediately draw is terrible.