I found it actually lengthened my step and gave me a better pulling movement on the track.
If you're trying to shorten your stride you drop your knees and dig into the track. This drill does the exact opposite. While the actual stride length decreases the amount of movement of the leg is greater because you have to bring it up higher than normal. Once you remove the restriction of the stride length the knees stay high but you also extend further down the track.
It's pretty damn difficult to raise your knees and still shorten your stride while running full out. I'm no expert but I'm pretty sure that it's impossible.
I have no idea whether this will work for anyone else but my form feels the best it ever has.
I should also note I'm doing alot of tripple jump excercises which help with cadence, strength, and stride length quite a bit.