For someone carrying a concealed weapon, a fast draw shouldn't ever be necessary. No one knows you have it and if you pay attention to your surroundings and what is going on, it shouldn't be a problem to have it in your hand when you need it, unless it's a face to face confrontation which is moderately rare.
For those times when you are in a FTF situation, you are better off practicing smooth access and at the same time, deflecting whatever your opponent has while you do. You should consider your hand or arm that is deflecting his weapon a throw away, and practice shooting your gun dry or until your opponent is no longer moving or you can see through him/her. That's what professionals practice if an opponent has gotten too close. This is called close combat, with the gun low and close in to your body while your off hand deflects, grabs or defends from his weapon.
Otherwise utilize the surprise that is on your side if the threat is some distance other than right on top of you. Smooth draw and employment of your weapon and fire when on line as the threat presents.
