When I did the pork shoulder I used the old style weber briquette. Filled the basket with a 3kg bag and it lasted 10hrs, think it could have gone another hour but wanted to get back to sleep so topped it up with a second bag. I used sand in the pan and it definitely didn't use as much fuel as I need with water in the pan. I put a smaller foil tray on top with hot water in it just to add some moisture. No topping up required. I've also gone dry pan when I wanted to hit the higher temps for the duck.