I designed the first two exercises to be suboptimal for developing acceleration, and lay down brackets for skill development. This is what it feels like if the stride is too short and if the stride is too long, so by the time the third one happens it allows my client to find their right means of acceleration.
Also if you quickly look at how Chris exits on the first drill compared to the third it shows perfectly why agility ladders do not make for good speed development tools. Even in the hub using only the 3rd rung is too much for effective acceleration. Any more rungs than that and you’re simply counteracting any speed you wish to develop to demonstrate an ability to pointlessly move the feet in a fast manner.
Please note, this isn’t a comprehensive guide to speed development just something of note to point out.