“There is nothing so useless as doing efficiently what should not be done at all.”
But how do you know what should be done, and what should not be done? How do you know when something should be stopped?
The only way to know is to have a clear view of your vision and the plausible promise you have made, and to measure everything in the light of those goals. Good deeds that don’t get you to the goal can be good, but time-wasters.
If you have a clear view of your goal, “stop” becomes much easier. It’s all a question of what you value – your goal, or what you’re doing.