I often tell my students to think of the shortest/fastest route between two points (home and school, for instance). If the goal is to get to the second point quickly and efficiently, we have to identify which route to take, and then we have to take forward steps along that route. If we leave the house and move backwards (in the opposite direction from the school) we are only adding to the number of steps - and the amount of time - it will take to reach the school.
By the same token, in practicing, it simply isn't worth our time to practice careless and inaccurate repetitions of a task, because doing so only adds to the amount of time it will take to master a skill or to polish a piece. Instead we should try to make every action a productive one.