While the vast majority of defensive gun uses occur at close range, practicing at distance is an important skill for all shooters to develop.
Once the armed citizen has advanced to the point that he or she can draw and shoot their defensive handgun safely, accurately and quickly, it would be a very good idea to start adding movement to the defensive response. Movement has the potential to momentarily confuse and surprise an attacker, allowing the citizen to gain a bit of advantage.
Training someone to shoot a defensive handgun is mostly a standardized process. Firearm safety is followed by firearm function, which is then followed by an introduction to the basics of marksmanship. Past that, focus falls on handgun manipulation, presentation and various methods of target engagement.
As Sheriff Jim Wilson points out, personal defense is really about establishing a series of good habits that you regularly employ.