How do you interpert the quote Slow is smooth Smooth is fast?

The "slow is smooth, smooth is fast" saying has its origins in the military. With that context the meaning is fairly obvious: moving fast, or rushing it, is reckless and will likely get you killed. If you move slowly, carefully and deliberate however, you are really moving as fast as you can without needlessly increasing the risk on your life.

The expression comes from the rifle range-it is what the instructors say to the people being trained regarding loading and unloading- aiming etc-it is a marine corps expression from the range that bleed over into other areas and then into the civilian world. semper fi