The vast majority of your defensive practice time is best spent working on a smooth, quick draw and placing a pair of shots into the vital zone of the target. Delivering quick hits—no spraying & praying—to the bad guy will solve most of the defensive problems that the armed citizen has to face. However, once in a while, it is a good idea to change your practice up just a bit to deal with other possible scenarios and to avoid boredom.
Take a chair and card table to the range and practice drawing and engaging targets from a seated position. This would be much like the situations that one might encounter at work or in a restaurant. This is also a good time to practice the same drills, but drawing with your weak hand. You do have a holster that you can access with your weak hand, don't you? And don't cheat, just wear your standard concealed-carry rig and covering garments.
Speaking of shooting from a seated position, when was the last time you practiced some pistol presentations while seated in your car with the seat belt fastened? However, you might want to practice these drills with dummy ammo and dry-firing, as spouses tend to get really upset with bullet holes in the family car. In a carjacking it is very possible that you will be attacked from the driver's side of the car and you may need to exit out the passenger door—away from the threat. Can you do this in your car? Have you actually tried to get over the console and out the other door?
My thought is not to try to make a contest out of these drills. It is a better idea to make it a study session. Get several of your shooting buddies together and set up some of these scenarios. Set up the problems and then discuss the best ways to deal with them. It helps you to imagine real-world problems that you may have to face. It helps you to understand your own limitations and to figure out way to deal with that, too. And it tends to break some of the boredom connected with regular square-range practice.