Lack of flow information? Poor gauge? Poor warning light? Still no excuse, in the end. Your fuel state is the second most important thing in your helo, after your rotor rpm, and about even with your altitude.
To misjudge is one thing, to run out of gas while fat and happy in cruise is neglegant to the extreme. On one model piston, with notoriously bad gauges, I simply punched the clock. At 1 hr 30 minutes, I would be on the ground, "one way or the other," my instructor said. I listened!