Yep, wood is harder at the knots. You're doing fine, just continue to take your time, and follow that ring wherever it leads. Enjoy yourself. Chasing rings is therapeutic. Sometimes I'll switch tools often between the gooseneck and straight scrapers, Bowyer's Edge, drawknife, whatever I think is most appropriate.
Oh, unless the stave is down at or below 10-12% moisture content, seal the back with shellac when you're done chasing for the day, otherwise it can check on the back and you'll have to start all over again.