Today I finished my first "pass" through Dounis Opus 12, and today I can actually play the Debussy Violin Sonata. B.D. (Before Dounis) I could muddle and guess through the piece, but now (I guess it would be A.D.) I can play all the notes most of the time.
I have not increased the amount of time I practice since doing my "row" of Dounis and Sevcik every day (it takes me about 45 or 50 minutes to do a "row," and I have been adding Sevcik bowing exercises), but I have improved the quality of my practice and the physical strength of my hands and fingers.
I absolutely believe that this kind of practice, switching from one activity and challenge to another, is the secret to achieving a state of technique on the violin.