Running drills help improve running form: If you are familiar with the basic running drills, you can see bits of your running form interspersed in the drills themselves. Without having to work on changing running form while running, you can improve the motor pattern you are using while running. Take for an example the C drill. In this drill, you flex the hip, knee and ankle to 90 degrees. Next you kick out at the knee, straightening the leg and then paw at the ground with a flexed foot and cycle through pushing heel towards the gluteals. The form change while running you can take from this drill is: landing on the ground with your center of gravity slightly in front of you to prevent too much stopping.
Running drills help improve muscle neuro-dynamics: Running drills are like mini plyometrics and as you progress through the drills, they gradually progress in speed and power. The drills are performed in a more ballistic style and faster as you go along. You may start walking and add in skipping to a drill. If you are new to these, you may notice legs feel heavy and uncoordinated. However, once you have completed the drills a few practices, you should be feeling more bouncy and fluid (more coordinated). Your body develops better motor programs in your brain related to the skill of running as you improve in this area.
Running drills make for a good warm up: Completing running drills will help prepare the body for an impending workout. The temperature of the muscle rises, blood gets pumping. Each joint should be gradually moved through its range of motion providing a stretch similar to the running motion.
Running drills improve flexibility and strength: Running drills make the muscles work through a slightly different range of motion than when running and will work the muscles in a different direction at times. Running drills also increase strength. For an example, including the exercise of high skipping (a bounding like drill) will add to muscle strength in the legs. This also will help improve stride length when the legs become stronger.
Running drills have the potential to reduce injury risk: Overall, drills will improve strength on one-legged stance since drills are typically completed by one leg at a time. This will lead to improved alignment of the legs when running since many drills are very similar to the specific activity of running. Also, running drills take the joint through larger ranges of motion thus stretching the joints in places you may be tight. To get the benefit of stretching, research now shows one must stretch at least in 3 minutes bouts to elongate the muscle. Completing a specific drill about the length of one minute 2-3 times can add to this practice of improving the range of motion around a joint.