Have you ever watched offensive and defensive linemen do so called “form running’ drills? It is the most nonathletic disjointed looking activity you could imagine, certainly the epitome of mindless exercise for this population. I think the players just go through the motions because they intuitively know it has nothing to do with the ability to play their position, it is another task they must complete before they get to the stuff that matters. Various permutations of from running including high knee skips, high knee running and pawing are predicated on having time in the air to recover the leg through in the step cycle- this is the opposite of what a lineman wants, for that matter virtually any athlete who has to change direction wants to do. To be effective they need to play with their feet close to ground in order to optimize their ability to change direction and keep their center of gravity over and inside their base of support. If you are using these types of drills for anyone besides a sprinter, jumper or hurdler in track and field you are probably wasting your time. I have heard the argument that they are good for hip mobility, yes they are, but there are better drills that have positive carry over to change of direction sports.
So what should you do? Jump rope, do ladder drills with short ladders, in short drills that emphasize getting the feet back to the ground with the hips over the base of support. Be creative and imaginative; devise drills that emphasize quickness in three to five second bursts. Drills that promote triple flexion of the ankle/knee/hip- the key to playing low. Playing low is rewarded in multidirectional sports.