Sorry, but I don't have time to go into all of it right now (I know you were just dying to know), but I thought I would share an interesting visual example of this particular maxim, one you can try for yourself and even demonstrate to a class.
All you need is a piece of scrap paper and a pen or pencil. Your task is to draw as straight a line as you can over and over, 10 times. First, do it as fast as you can. Then do it again, but go as slow as you can. Below is the result of my attempt:
If you practice your technique as fast and powerful as you can all the time you get a technique that is fairly scattered, with varied results. However, if you practice slowly and precisely, your technique tends to be more consistent and even more intense.
Just something to think about. Happy training!