The most successful coach of US Olympic archers recommends string walking, especially for folks who are used to shooting with sights (us guys who have returned to recurves after a long time with compounds, sights, and release aids).
For about 9 months (December 09-early August, 2010) I had been shooting 3-fingers under with the index finger touching the arrow nock. I was shooting gap, not instinctive. I was "ok" at 15 yards but not happy beyond that. I even qualifed for the IBO worlds using this system and came in second in a "money shoot". I left the money with the club -- I was just trying to get hunt'n ready. But I had a lot of work to do.
Then I watched this fellow's video (that he sent me with his Recurve) and learned how and why string walking might be good for me. What the author says is that he does fine on targets gap shooting. But in the heat of the moment when hunting he often shot high. He concluded, because he was used to using sight pins, when a hunting shot presented itself he subconsciousuly forgot the gap and used the point of the arrow for reference. Well, at distances under 30 yards most people will shoot high if they put the arrow's point on the spot they want to hit. You have to "look low" to hit at such close distances. By the way, this fellow, who's initials are TS, holds NFAA records that are decades old. I don't know how deep his age is into the 60's but he's my senior and he has returned to competitive archery this year.
I then began experimenting. I'm not going to claim I started to robin hood arrows, but my groups became tighter and I immediatly became confident at 20 yards and could see that 25 was going to happen also. I'm very happy with this aiming style.
Yes, I have to know the range, but not to the yard though. For me, if I drop my 3 fingers to a spot on the string that is just a bit more than an index finger width, below the arrow nock, I can place the point of the arrow on what I want to hit at 20 yards. Almost like a sight pin, albeit a big fat one! An index finger and a half and I'm good on anything under 15 yards. My arrow point is right on at 35 yards (under the heart at 30)--but I won't consider a hunting shot past 25 yards.
I basically serve a very wide nock locator (serving on top of the center serving) under the arrow nock in one color for 20 yards and then another color below which I'm on at 15.
About aiming. Just like with sight pins, if you concentrate on that sight pin, trying to keep it still and focused, you won't like the results. Your group's will be larger and you'll have a difficult time following through. Aiming with a bow (sight or arrow point) is more like aiming with a handgun (open sights). You look at the spot you want to hit while your mind's eye places the sight or arrow point there. It is amazing to me that your mind can do this very accurately if you will let it -- thus my "signature line".
This fellow has a DVD explaining the entire process which I'd be happy to direct you to via PM.
Will I always do this? I dont' know. But I can't tolerate "to whom it might concern" or "shotgun" accuracy with a bow. I want to hit the hair, shadow, or crease I'm looking at with my hunting recurves.
My return to recurve hunting after 34 years of compounds, using this system resulted in 16 and 21-yard clean kills on deer this past season. I was very tickled!