Just to add my thoughts this does sound slightly ridiculous, but having travelled in all cabins, it is certainly true, that on the long haul flights, at the pointy end they will happily re-fill your glass as long as you let them really.
Never had a problem at the back, but often need to go back to the Gallery to ask for more, to stop pressing the old call bell, and also good for stretching the legs when 'at the back'
My view is as long as your not drinking too excess, it's a good aid to sleep and does help pass the time...
