We (GA) still have an average of 1 a week that try to get an internal combustion engine to run on air. The FAR's state what the reserves are for the type of flight. Personally I use 1 hour, yep on long x-countries I stop more than I should but I'm not in that big of a hurry or i would have gone commercial. Knowing exactly how much fuel and where its at is a huge plus if your going to push the minimums but for me, a "Stick & Watch" gets me to my next fuel stop, besides I would much rather stretch my legs than my fuel. Oh and if mother natures calls, I land as well.