Brilliant! Saved for bedtime reading.
Makes a lot of sense: to have one as a production check, since it wouldn't take up much room, and to divide it down to get a sensible answer.
I wonder if the other two (and maybe this one) came as part of different lumps of silicon, e.g. the Vc and the ARM. There wouldn't be much gained by removing them when the lumps were combined into one large wafer.
Now to find a use for it.