The main comment I have about Ed's article here has to do with his distance calculations. I find that there is considerable variation from person to person in the distance at which a given throw will make a knife stick. You have to find the distances at which your baseline works for you . Once you have accounted for individual variations in the basic one half or one turn distance, there is the matter of holdover . Holdover is familiar to shooters of all kinds, not to mention people who throw lots of rocks or baseballs.
Gravity begins to affect a projectile the moment it is released.
That means you can never shoot or throw straight at your target, but always a little above it. The further from your target you get, the more pronounced the holdover becomes because the pull of gravity is constant for every millisecond the projectile is in flight. This means that a knife travels a little farther to the target than one would think. A knife released 10 feet from its target might travel 10.5 feet to get there. At 20 feet, the knife must travel an arc of not 21 feet, but perhaps as much as 23, because the effect of gravity is cumulative.