All these durations would probably last 50% longer on an alkaline battery, due to the very low currents being used. I don't want to test that, because I don't trust that an alkaline wouldn't leak when it gets down to 0.85 volts.
I tried a 0.63V alky and it would not even start up a H51w. Using a 1V alky, I could not switch to any modes and it came on in sort of a medium-low mode. This is a H51w (third revision I think). It may be different if you start it off with a new battery though.
That said, I think you can get 150 hours at 10mA constant draw from an AA down to 1V.
How good are your multimeters folks?