Is that correct? Only 3 hrs run time @ 10 %?
I suppose if you left it on continuously, it would last three hours.
I rarely have it on for more than a few moments, to find house numbers.
The on button can be used as a momentary switch - the light will come on only while you depress the button, or you can fully click the button and the flashlight will stay on.
I've had this flashlight for two years and I think I've changed the batteries once...