One thing I'll throw in is some woods, like snakeskin sycamore, have got a hook to the grain. You'd want to make sure the flow is going the same direction side to side. Aside from that, in my case a lot of my knives are double bolstered, so you can't see the end grain anyhow, which is where matching the grain flow, or intentionally going against it, can be additionally attractive depending on what you're trying to achieve.