I used to shoot defensive handguns at 7 yards and 25 yards and NEVER at less than 7 yards. I think it is prudent to practice at least a few rounds at distances even shorter than 7 yards but generally speaking, I think if you can do what needs to be done at 10 to 15 yards, you're in good shape but drawing from concealment and quickly and as safely as possible and remembering to disengage all safeties is the most important aspect of preparing with your defensive arm.
I also enjoy shooting at 100 yards, mostly with a Dan Wesson 22 revolver.
For long guns, I guess 100 yards is the magic number. With scoped rifles, I usually try for the smallest groups with no more than about 5 seconds from taking it off my shoulder (as in carrying it in a sling) to taking the shot. I've not done much droping to a prone position kinda stuff... but I probably should. And with the AR, I've set up several 10" x 10" x 8" boxes on the flat end and varying distances from 15 to 50 yards and kind of shot them in rotation with reasonable quickness.