maybe the zoji is not made for that scale? and the water mark is not linear for that small cook?

i use my zoji with minimum quantity of 1 cup. on the smart/neurofuzzy/whatever model, timing is ~40min for a full cook (though the timer indicates 60), and ~20min for an abbreviated cook (though the timer indicates 40)

funny thing about rice:water ratio.
the western rule of thumb says 1:2.
the asian rule of thumb is to go 1 knuckle above the rice [should be called rule of index finger?]
the real asian way is simply to eyeball

none of which is really consistent with the zoji way