I have better luck pulling into the fresh ring. So essentially how the picture is. If I rotate and pull into they upper rings I end up with tear outs more frequently. I'll work in sections about 6-12" long. And work my way down the stave. Depending on how deep I go it takes from 15-45 minutes. I hog away to the ring above the one I want, then slow down for the cleanup and make a lot of use of a scraper. On the last ring I will remove the late growth with the draw knife, so it just reveals the crunvly early growth. Then I take the scraper to the crumbly wood to clean it up. Doing like that I rarely damage the back ring anymore, unless I get distracted while chasing the ring. Which seems to happen pretty easy.
Kyle