ozboy

I think it is a good idea to keep a diary record of your practice. Put a book on your stand and jot down what you've done as you do it. It builds in rest time, it helps you maintain a focus on what you are doing and it gives you a 'warm and fuzzy' when you look back each day/week/month and see what you have achieved. It can also isolate problems and build a balance into your practice.
This obviously endorses the 'quality' theory.