When hunting ducks with a shotgun, you do not shoot at sitting ducks, you shoot them in flight. Duck hunters know you can never shoot at a duck in flight. If you do, by the time your shot pellets reach where the duck was, the duck will not be there. To shoot the duck, you must quickly determine the direction and speed of the duck, the range to the duck, and know the speed of your shot pellets and how long it takes them to cover the distance to the duck. Using this information, you must then instantly compute where you think the duck will be when your shot pellets reach it, allowing for your time spent making and analyzing the computations and the time it takes you to aim and shoot, and then finally, you must accurately shoot at that point in the sky. If everything goes as planned, you will hit the duck and be having roast duck with your friends while you all sit around the campfire. If you will miss the duck, the other hunters will be roasting you as you all sit around the campfire eating wieners.
When you spar, most opponents are constantly moving, so you cannot kick where the target is located; if you do, it probably will not be there when the kick arrives. Since your hands are so quick and maneuverable, you can usually punch at a target and hit it before it gets away, but kicks have too far to travel and a leg has too much mass for it change direction quickly, so you cannot count on the target being where it was when the kick fired.
Once you spar a few seconds with an opponent, you begin to see the how the opponent reacts to your kicks: which direction they usually move, how quickly they move, and how much they move. You should use this information and start leading your targets. Instead of kicking where the target is, kick to where the target will be when the kick arrives.
Sometimes you also have to lead your hand targets. If your opponent leans backward away from your punches, then you should extend the range of your punches. If the opponent drops under punches, then drop your punch immediately after it fires so it hits the lowered target. If you opponent slips to the side to avoid punches, then punch to a point beside the head. If you punch at the head, you miss every time. If you punch to one side of the head or the other, you have a fifty-fifty chance of hitting the head.
Sparring targets are not sitting ducks; they are ducks in flight. So to hit the targets, learn to lead the ducks.