Over and over again in my development towards being a professional violinist, I heard "Practice makes Perfect" or ( its supposed improvement) " Practice doesn't make perfect, Perfect Practice makes perfect". I completely understand the idea and intention behind these familiar sayings. And I agree, you have to practice the instrument to accomplish anything of value. I could even add with certainty, that the more proper and appropriate practice that you do , the better ( or more perfect) you will get. However, the set up of the paradigm that 'perfect practice leads to perfection' is one that , more times than not, will lead the practitioner to a needlessly disappointing outcome.
The truth is that no one plays perfectly. Expecting perfection is inviting the shattering of the facade that was never possible in the first place. The greatest musicians that the world has ever seen made mistakes probably on every performance....and no matter how much you practice (or how perfect you practice), chances are you probably won't perform perfectly either. The more advanced in string playing that you get, the more you understand this to be true. I believe that playing a musical instrument is important and beneficial on many levels. There is the benefit of self expression. There is the importance of providing a respite from your (or your audience's ) daily concerns. Yet, I have found that there is another benefit that is experienced in the pursuit of playing a musical instrument, and that is as another potential surrogate of 'life'.
Along the lines of another familiar saying 'stuff happens', no matter how perfect you practice, stuff will also happen. I believe allowing for the possibility of that "stuff" happening puts you one step closer to accepting and dealing with it successfully through immediate self-forgiveness towards transcendence. I think of it as getting to the mindset of 'it happened let's move on'. This is the way of the artist. The world's greatest artist played with a high, almost unbelievable, level of consistency. Yet, their true wizardry was , when the imperfection came, they handled it with an equal level of artistry. I believe that it is in the endeavor of practicing towards perfection that one should also practice this. That is to say, that in some point of the practice, there should be a concerted effort to acknowledge the mistake, forgive yourself and move on. One of the truly valuable gifts of the effort of in-depth study and repetition, is that it allows you to practice handling the imperfection quickly and in the most seamless way possible.
So practice towards perfection. Hit that lick ten times in a row. Strive to nail that F natural perfectly every time it presents itself. But also, practice the art of forgiveness and moving on. Lord knows that you'll need that trick too.