There will be a lot of movements in Jiu Jitsu that require both speed and accuracy. Some will require a little more speed, others will require a little more accuracy. In order to define accuracy a little better for our purposes, I equate it to being able to put pressure on your opponent and move with precision so as not to let up too much. The problem is, when speed is emphasized, accuracy will have to be sacrificed. The same is true for when accuracy, or pressure is needed, speed will be compromised.
In 1954, Paul Fitts, a psychologist proposed a mathematical formula that suggested that movement time will increase linearly with movement difficulty. In other words, the harder a task is, the longer it will take to execute. This results in what is known as the Index of Difficulty. This has quite a few implications for Jiu Jitsu, particularly with respect to guard passing. When passing the guard, you have a couple of main systems of passing. Either you can a) put lots of pressure on your opponent and pass slowly and technically (accuracy) or b) you can use your agility and quickness in order to pass (speed). You cannot really pressure pass quickly because there will be too many mistakes. On the other hand, you cannot be too accurate with your quick passing from a distance because it will take too much time.
One concept that has helped me develop both is by drilling my guard passing slowly and technically. Making sure your movements are precise slowly will help you practice them quickly. You will learn how to “be slow in a hurry” and