I usually create two or three queue templates during a game. Early on, I try for mostly science and happiness improvements first then productivity improvements. I either add on to the first queue or create a second one as I get more advances. Somewhere in the middle of the game, I find that I usually need more productivity and money improvements, which is why I often just create a second queue. Toward the end, I almost always just do a productivity queue with a couple of happiness and money improvements thrown in for good measure. I usually have plenty of money and advances toward the end of a game. If I'm lucky, I don't really need the productivity gains as well, but I've normally built the queue by then so I just keep using it - cranking out those War Walkers (or Fusion Tanks, or whatever).