Thus, in mining, this will automatically add all the available smelting ore into bars, but will not add smelting tin and copper into bronze. In Engineering, it will add grinding stones into blasting powder, but will not add making bolts out of bars. I have no idea what this will do in other skills (alchemy, leatherworking, blacksmithing). I can only assume it is something "reasonable". Please let me know how this works for you.
At any rate, all this does is add things to the list. You therefore have a chance to look at the list and edit it manually before hitting "Do" to actually perform the steps.