I started chasing growthrings with a dull drawknife. Probably saved a lot of growthrings from premature death!!! Now that I have some tool technique I want my drawknife as sharp as my broadheads.
Like Okie, on a well seasoned and uncomplicated stave, I can get 'er done in about 30 minutes. But that's rare. It's more likely a couple hours. I always stay well away from pin knot clusters and dips in the grain. I often use a 1/4 or 3/8 inch curved gouge type chisel and slowly pare away the wood around the knots and dips. I have done one mulberry with something like 20 clusters of pin knots that took almost 15 hours of work to get to a growthring. Used the little gouge for the whole thing, scraped with a small pocket knife. That stave likely took 8 years off my life. Can't say how many times I ran out of expletives and had to go buy more!