Totally incorrect: as we already mentioned, this blast furnace actually costs just as much as every other blast furnace to run all the time (which they do). The difference is only in the outputs, which I described in my post and now repeat below, with emphasis this time.

Let's also imagine that the blast furnace changes behavior minute-to-minute (usually in the middle of the process) between useful output, useless output (requires scrapping), and counterproductive output ——>(requires rework which exceeds the productivity gains of using the blast furnace to begin with)<——

Does this describe any currently-operating blast furnaces you are aware of? Like I said, probably not, for good reason.