Do, everyday, all that can be done that day - doing each separate act in an efficient manner - Wallace Wattles
Efficient action is a topic I've been studying carefully as of late. It's an incredibly simple idea, and perhaps this is why it is often overlooked. Action can either be strong or weak - efficient or inefficient. Strong action is guided by a concentrated mental vision, while weak action is derived from a distracted mind.
It's not the number of things you do in your practice which matters - it's the full concentration behind each seperate act which matters. Remember that the the body/mind is one unit. If the mind is not fully present, the physical act will represent that. We want to be fully present in each act with a clear mental vision guiding us.
I recently had a wonderful lesson with a student who was having problems with buzzes in the left hand. We tried many "tricks" to get her left hand to fret cleanly, but the problems persisted. I suddenly realized that the student was not guiding the left hand with her mind. She was pressing on the correct frets, but because she didn't have a clean sound in her mind, the left hand was acting inefficiently.
I then asked her to hear the piece clearly without buzzes in her mind. I told her to keep that imagined sound in her mind as she played through the piece no matter what happens. By concentrating on the clean sound, her body started to find the way to get that sound. The playing instantly became much cleaner. This is efficient action.
Keep your mind on the vision of what you want while you work - no matter how distracting the mistakes may be. Stay focused upon what you want and act towards it with your full concentration. When a mistake appears, acknowledge it - but stay focused upon what you want and continue to act with the clear mental vision guiding you. You can only progress with this kind of work.