The cruelest workout known to soccer players world wide. It sucks!
When I was 52 and my 18-year old daughter was trying out for an NCAA soccer team, this was incorporated into a three month PT program. It not only gives you a bench mark for measuring your stamina and speed, it improves it. It is somewhat like "testing to destruction" though.
I forget what level we each achieved, but we improved markedly as the summer progressed. The US Men's Soccer team uses it and some of the levels these guys reach are phenomenal. While it rewards both speed and endurance, my opinion is that rewards endurance most.
Try it. You'll hate it. But it will be good for you. It should be incorporated into an overall program.
Tyson