IMO - it is the #1 drill. I have been at this a long time and tried pretty much everything out there and this drill not only feels right (once you learn how to do it correctly - and a footnote that many other so called drills feel absolutely wrong no matter how much you do it) it leads to the other few drills that can be applied to your regular swing. Once you figure out the SnF you can apply to these other drills
Rear Leg Swings
Deep Tee
Reverse Top Hands (done with a rearward turn of the barrel)
Modified SnF off front toss / machine / live
There are two drills that really helped me. First, the SnF drill. Second, Tewks' "step open" drill. I think he can provide you with more information on that one.