In Pure Krav Maga the reaction time principle calls for efficiency, the economy and maximum effectiveness of a motion. These factors call for the concept of Sequential Execution.
For example, since the arm weighs less than the rest of the body, a punch should start with the fist, pulling the arm and only when close to the target, the shoulder should twist to facilitate weight shift to the impact zone.
While this ensures the mass is moving to the right direction in the right time, it also enables the fist to start the acceleration process from zero speed to maximum speed at impact, without waiting for the greater mass - the rest of the body, to start.
In kicking, seesaw motion or corkscrew like motion and combinations of both of these, allow the torso to leverage accurate mass shifts in the kicking directions.
When it comes to defense, the Sequential Execution concept again, allows the inner or outer forearm, the wrist, the palm and the bottom of the foot, to start the motion first when possible making the defense as efficient as possible, enabling to execute the defense in the last possible moment.
For evasive body moves, it is important to recognize that the throw of the shoulder, or the head to the side or downward, the twist of the hips or torso should start the motion when push comes to shove.
That sequential execution of attack or defense is built-in to any attack or defense method coupled with the tactical implementation to prevent any possible follow up attack. This is done by re-positioning the body and limbs in a convenient location or/and understanding and drilling follow up attacks or defenses which are possible under the constraint of the reaction time.
Finally prioritization is the principle that is added to the mix, and it helps determine what is preferable of all options available in each scenario.
Let us not forget, that in attempting to drill reality based self defense, we should be very careful not to make means of control methods other than striking, tearing or cutting constricting pressure points into ends.
This is simply because if we assume that a trained opponent will have enough reaction time to recuperate and counter our efforts, we are simply wasting our time in unrealistic expectations from our thoughtfully designed drills.