BUT your question, now answered, deserves a more lengthy answer (and every knows I'm good at that!).
You should have enough gas, while the "reserve" is flashing, to travel 40-60 miles, or more, to refuel. Prudence would dictate that this should not be a habitual modus operandi. The gas in the tank also cools the fuel pump. If one were to ride their bike well into reserve every tankfull, it might be assumed the heat and possible added stress could shorten the fuel pump life cycle.
(Just one man's opinion)