As a matter of perspective:
-I have read that optimal cadence for cycling is 85-100/min., roughly the same as running.
-I teach rock climbing, and one major technical difference between beginners and experts on the same terrain is that the beginner tends to make bigger reaches and bigger steps, while the expert seemingly "floats" over the rock with a series of quick, small steps. Keeping your feet underneath you results in greater overall efficiency on the rock, and it stands to reason that a similar thing is going on in running, epecially over hills and rough terrain.
-One thought I have had is in racing, it might be best to keep a high turnover through most of the distance, so that in the final kick, one can lengthen the stride (same cadence) to recruit fresh muscle units and resulting in a faster, more powerful closing. It is also easier to accelerate from a higher cadence and farther up on the balls of your feet, thus catching your competition "flat-footed", both literally and figuratively.