I have to admit that I've not spent any significant time reading the works of Lauren Seagrave.
However, I recently found a PDF version of his Speed Dynamics Video Series.

To be fair, what I read was a summary outline of the content of the videos listed.
That being said, the first "Mission Statement” was about the importance of reduction of ground time or air time by .01 seconds at every stride.

The Mission Statement followed with a chart showing the benefits obtained at 40 yards (?), 100m and 1600m.

The chart showed that at 20 strides of the 40-yard run, a .01 reduction in either ground or airtime would produce a .20 second improvement in running time.
At 100m, the improvement was .50 seconds.
 
The benefits:  Improved efficiency; quickended(?) neuromuscular response; heightened awareness and increased general and specific strength and power capacities.

All of that just by reducing either ground time or air time!

One of the charts had some of the nifty standard cues to help:
"Toe Up"
"Heel Up"
"Knee Up"
"Step over the opposite knee"

Ok, all of this sounds great, but...

How does one reduce airtime?
 
Why do faster runners have longer airtime? What are they doing wrong?
Faster runners do have shorter contact times as a result of high rates of force delivery (no one knows for certain why faster runners have higher rates of force delivery than slower runners) but how can slower runners simply get off the ground as fast as swifter runners?

Heightened awareness? The fastest runners have ground contact times at or under 0.08 seconds. Force delivery occurs in half that time. That does not leave much time to be aware of either what you are doing or what you are seeing.

Moving on to the nifty standard cues, why would it matter if the toe was up or down at ground contact if ground reaction force is greater than 2x bodyweight? Is it possible to keep the toe down under that amount of force anyway?

The other clues do sound important.
What do they actually do in the air that will help the runner on the ground?

Finally, according to research, "If the mechanical energy to reposition limbs is provided largely passively through elastic recoil and energy transfers between body segments rather than actively by power generated within muscles, minimum swing time would be affected minimally by muscle fiber speeds." Weyand, et al JAP 2000

Clearly, the drills mentioned above, "Toe Up","Heel Up","Knee Up", and "Step over the opposite knee" requires power generated within the muscles to effect them.
If that is the case, what is the point?

Frankly, these drills appear fabrications of what one sees rather than what actually occurs at high speed.
That being the case and apologies to Mr. Seagrave, but I will continue to rely on legitimate research rather than guessing.