In martial arts it is always necessary to feel out the level of reaction time with your techniques. Sparring has always been the step that is used as sort of a bridge between fighting to make sure that your balance, timing and accuracy are up to par. Everyone has there own rules on whether they wear equipment or strike to the face etc. Controlled sparring should never go passed 80 percent of your effort because then it gets more dangerous for both or all participants. The unfortunate truth is if you have not taken the time to practice all of the techniques to the point they are natural and effecient, then you are just wasting your time. Sparring is the step you take after you want to test your attacks and defenses that are "solid." The sparring will give your techniques timing and understanding but not help with speed or power. Therefore if you begin sparring too soon, you will never have powerful techniques. On the other hand if you never spar you will never know timing or feeling out your opponent. So as with all things there must be a balance.
The first step is too make sure my technique is mastered. Lets use the spin kick for example since there are not too many people that have trained it fluently. First I practice my spin kick in the air over and over. Until my balance, speed and force are all connected. Next I train my accuracy to make sure I can hit exactly what I am aiming for. I usually tape a few pieces of paper to the wall no longer than a finger nail. Tape each piece of paper at various heights because as the height changes, the range changes. First I practice the single spin kick as fast as I can, kick the paper without kicking the wall. After it is easy to do a single movement I can now apply it in a combination. Throwing 3 to 5 kicks as fast as I can. This lets you fix and adjust the footwork and range between each kick.
Now I am ready for two person drill training. The idea of two person forms or drill training is that you begin to teach muscle memory of your reaction time. So it is important that with many of the drills that you are really trying to hit each other if you are training your defense. Whether you are practicing with swords or barehanded the idea is to do the exercise repeatedly so that the movement is trained into the back of your brain. You may find that while doing this type of training you might punch in your sleep or automatically strike a friend if he sneaks up on you. (By the way...Don't ever sneak up on martial artists.) But with two person training exercise it is ideal that both people are training the desired technique at the same time. Person A starts the attack and person B counters on and on and on and on.
Now my technique is ready for sparring. I have learned control so my partner won't get injured. I have learned balance so that I won't get injured. Timing is the most valuable factor that can be learned from sparring. To use an effective spin kick is the same as your opponent stepping on a landmine. Just as he is committed to the exact range BANG. This is where it is important to catch your opponent between thoughts. As he changes strategies or ideas he is unable to calculate his position. Which is why Bruce Lee used to use vocal distractions when he was fighting against Chuck Norris.
The unfortunate truth is that most people rush to sparring without ever rigoursly training their technique. In a microwave society everyone wants everything right now. We want the power without the purpose. True martial arts is having to refine ourselves to the very core of our weaknesses. When we are fighting with another opponent we are actually using each other as a gauge to understand how we need to improve. Therefore winning or losing should never be our focus. If I define myself by beating others then I only need to be as good as the person infront of me . This is the cause of a lot of arrogant martial artists which in itself is an oxymoron. Arrogance is birthed from our insecurities of not being accepted, good enough, or strong enough. True masters never compete unless it is connected to the battle of self. The only battle worth fighting.