Regrettably, control is not stressed in martial arts training as much as it was before the advent of protective sparring equipment. In the past, to score a point, the technique had to be full-power, full-extension and within an inch of the target without hitting the opponent. Now, with protective sparring equipment taking most of the danger from accidental strikes, control is not considered as important. However, if a trained martial artist ever strikes another person in the real world, even if in self-defense, and kills the person, the martial artist may be charged with murder. The courts assume a trained martial artist has full-control of his or her strikes, so, if a strike kills, the courts may assume the martial artist must have intended to kill.
In a case a few years ago, after a martial arts demonstration at a shopping mall, a black belt was signing autographs for some young women. One of the women's boyfriend got jealous and attacked the black belt who punched the attacker. The attacker fell backward and died. The black belt was subsequently convicted of voluntary manslaughter, vice involuntary manslaughter or justifiable homicide, since the jury assumed that since the martial artist was training in killing techniques and control of power he must have intended to strike the man hard enough to kill him.
What if your opponent suddenly changes the range after you have fired-off a technique? If your opponent increases the range, you are in no danger of hitting him or her but you may be tempted to extend your technique further than originally intended and reach in an attempt to "catch-up" to your opponent. Remember, the target for all techniques is a point in space. That point may be on the surface of your opponent's protective helmet. If the helmet moves, your target point does not move with it. So do not reach after the opponent, just complete the technique to the original point in space and then fire-off another technique to another point, after adjustments are made for the range change.