Yeah and it needs 3 Raw-Stones to make one cut one.
Way more Vlies than it would actually need to make one yarn.
And ores are probably somewhat off aswell.
Looking at my current cooking, I need 3 loquats to make 3 bottles of juice - when in realty I probably wouldnt even get half a glass out of them.

Classic case of "gameplay over realism". If it helps your headcannon just pretend that you're always sawing 3 practice-pieces that your character throws out before the final, foruth attempt.