FWIW, there are three ways, as far as I can tell, to end your approach.  Plant, stop, slide.  I'm trying to learn to stop (like Haugen) because my knee is so unstable that I no longer trust it in a deep slide like I used to have.  Seems to me that my accuracy is better with the stop and I surely don't worry about my knee collapsing under me as I used to do.  I don't like planting - I think it's too much stress on the knee, hip and back (but what do I know?)  So, I guess my advice is, if the guy is really stopping, not planting, let him be.
--------------------
"Things fall apart; the center cannot hold; mere anarchy is loosed upon the world,"
I'm Ragnar Floggurass, and I approve this message

Brickguy, in my mind the difference between plant and stop is a matter of, for lack of a better word, aggression and torque.  Planters, imo, have a more aggressive style, with a more defined placing of the foot down at the line.  They will tend to be more open and create torque around the joints in the leg/hip.  Guys who stop take their steps, then, basically, just quit walking.  If you can find any film of Haugen I think he's classic at this.  For me, I do what I call "Stork-legging" it.  I take 4 steps, then remind myself to finish like a stork, with my left knee straight as much as possible.  I suppose there is a very small slide, even with my leg straight, but it's extremely minimal.
--------------------
"Things fall apart; the center cannot hold; mere anarchy is loosed upon the world,"
I'm Ragnar Floggurass, and I approve this message