you want quality, not quantity!
Many times I hear students that can play all kinds of fancy stuff, but it doesn't sound good. And it's important to remember that most listeners couldn't care less about how technical something is, they just care about what it sounds like and how it makes them feel!
So I added in a 5 minute Quality Control session into my practice routine and it really helped my tone. I also use it when I get a new instrument and I want to really focus on getting the most out of it.
When doing this exercise, don't worry about which notes you play, just concentrate on the sound, the tone, the texture of it and make it as great as it can be!
Amazing what can happen when you really focus on something.