In his book Pumping Nylon Scott Tennant makes a good observation about speed. He notes that when we look at an entire work you can notice that the fast parts only last for a measure or two. What answers can one draw from this observation? Some of the answers I have drawn are that while it is helpful to know your scales and play them quickly, it is not necessary to play them at break neck speed for lengthy periods of time. One of the things that can help us develop stamina to hold out during those passages is the daily practice of speed bursts.
A speed burst is taking a small portion of a scale and playing it ascending then descending with the eighth note as the rhythmic value for each note. Without stopping play the same portion of the scale ascending and descending, this time using the sixteenth note as the rhythmic value for each note. These are very helpful in isolating certain trouble spots in a scale, such as shifts and string crossings.
As always my advice on practice does not change. Practice these exercises with a metronome, slowly at first to “feel” each movement and help get it into muscle memory, then as it becomes more familiar to the body, increase the tempo. Remember that the illusion of speed can be achieved by playing the notes evenly. Sometimes people are not playing as fast as we think that they are, what they are doing is playing with strict, even rhythm. Use different finger combinations. Use i-m, m-i, i-a, a-i, m-a, a-m. The examples I have given you are only a scratch on the surface of rhythmic possibilities.
Also, in parting for this week remember scale speed is a most coveted aspect in ones technique, but in and of itself it is useless.
Playing ones scales at warp speeds can be likened to a poet that can say his abc’s at light speed. In the end neither does any good to bring out the true feeling of the word.