I have never been cut off in any cabin, and I have actually gotten fairly hammered in the premium cabins (which induces sleep). I have only ever seen one person cut off, and that was a 40 y.o. Gulf oil worker on his first ever plane flight, complaining that he wanted a female FA (on America's Worst). My experience is that if you're polite and obviously capable of behaving yourself, the FAs will gladly serve you, assuming we're not landing, etc. OTOH, LH *will* determine what the proper alcohol to have is (i.e., no Bailey's before dinner, that sort of thing).