According to the Craftsy blog, spinning long draw is a great way to create light, soft, fluffy yarn. As you spin, air is trapped between the fibers, which creates a warm, nicely insulating yarn. Long draw spinning can be a bit frustrating at first, because you need to manage your fiber and twist a little differently than in short draw spinning, but it’s a lovely method once you get your rhythm down. You can spin long draw with wool, silk, alpaca and other types of fibers.
Craftsy's photo tutorial found here demonstrates the technique of Long Draw spinning with wool.