Popper 7 is a fantastic study if you are interested in Feuermann/Greenhouse/Starker's "walking finger" technique. It is great for learning how to throw down fingers in groups of three or four instead of having to think about each note.
Take the first four notes. If you throw your fourth finger down and then sort of peel the fingers off by pulling back your left elbow you can play these notes in one motion. Then, because you pulled your hand back your fourth finger is "cocked" to be thrown back onto the starting note again by flinging it with the whole arm (like you were going to throw a ball onto the fingerboard!). If you do all these motions fast the first five notes sort of become one circular pattern. You can apply a similar strategy to every 5/6 groups of notes. I found that after learning Popper 7 in this way I could play it at a MUCH faster tempo then if I had tried to play it with a more square hand (my first teacher told me to play with a square hand so the fingers were always right above the notes). I find that this sort of "throwing and peeling" technique which necessitates a highly angled hand has improved almost all aspects of my left hand technique (i.e. I can play faster with more accuracy and more variation in tone colour and vibrato -- mostly due to the fact that this technique becomes literally impossible if you don't relax!).