Duxx,
I agree with your first point.
I don’t think that the exercise you propose is a good choice and I explain why, having done that many times and more.
Speed = relaxation and if you put the fighting in it, relaxation (if it is not in the ahtlete, and it is not most of the time) is the last thing you find.
More on that. A big problem in non-track athlete is poor technique, usually related to low (specific) strength levels. I began filming athletes and I noticed a common trend, very weak glutes and thus inefficient acceleration (pelvis up not the side pushing or hip internally rotated). If we don’t fix those issues in isolation (and that mean, in this context, without the ball) we are greatly limiting the exploitation of the athlete’s potential.
So, technique, specific strenght and relaxation must be tackled in isolation, even in team settings (the more exposure you can have, the better).
Lastly, every time we did that drill, I kinda felt that an injury was close. Not the worst drill in the wrold, far from it, but it must be put in the right context.