In order to become a skilled knife thrower, you must be able to have very quick reflexes. You need this in order to throw your knife very quickly at your target as some of your targets are going to be very fast moving. In other words, you need to build up a lot of speed and also mental reflex in dire situations so you’re able to hit those targets that’re unpredictable. Without quick reflexes, you wouldn’t be able to hit your target very effectively.
Another attribute of being a skilled knife thrower is the ability to be very precise and hit the target 9 out of 10 times. Without this feature, it’d be pointless for you to miss the target multiple times and only hit it only once or twice. A good way to improve your precision is to first analyze the target and try to get as close as possible. It takes some critical thinking in order to be get close enough with your knife, but you need to make your mind think faster with fast moving targets. Basically, you need both a quick and analytical mind.
Finally, you need to always be calm when focusing your knife on the target. You don’t want to hit the wrong target or possibly injure yourself. You need to be calm because you’ve a dangerous weapon in your hand and it could affect people if you lose your cool. If you’re not able to keep calm or you’re in an extremely bad mood, I suggest you rest and chill for a while, and stay away from weapons for about a week or so until you’re in a better emotional state.
How long it takes for people to be a skilled knife thrower depends on their quick capacity to throw very precisely and pick up on the fly. It also depends on how quick your reflexes were before the training, along with your ability to keep your cool during some of the most dangerous situations. I said this because people's learning capacities are going to be at different speeds and have different ways of target practice. It takes time and patience to master knife throwing.