I've been reading through the tutorials and discussions about cubemaps, and I think I've got the general idea. It's important to place them near shiny things and areas with changes of lighting. But what about outdoor sections with no water? How close together should I place them? I guess what I'm looking for is a rule of thumb on how many cubemaps to expect to place on a reasonably sized map. As an example, how many cubemaps would you expect to see on something the size of, say, the first stage of Goldrush?