That is true, but the teeth in a Japanese crosscut saw are very delicate and fiddly and there's lots of room to screw them up if you don't care about the produc

That is true, but the teeth in a Japanese crosscut saw are very delicate and fiddly and there's lots of room to screw them up if you don't care about the product. And yet (with some exceptions) they actually seem to come sharp from the factory, something that is still a novelty in Western tools. They're not all good--I have a modern pruning saw that is particularly crudely made--but they're startlingly high quality in an era that has seen near total collapse of, say, chisel manufacturing[1]. I suspect the tendency toward impulse hardening the teeth made it vitally important that the teeth actually be ready to use, because it would take a diamond file and some real patience to sharpen them after hardening, but I really don't know. [1] A chisel is a bar of metal with a wedge at the tip and a handle. You'd think it would be pretty hard to screw up, but you underestimate the ingenuity of idiots. From using the wrong steel, to forging it wrong, to hardening it wrong, to grinding it wrong, to putting the handle on crooked, any and sometimes all of these have been spotted in the wild. I would no more use a department store chisel for woodworking than I would use a screwdriver as a drill.