The answer, of course, is "it depends".
I am out hiking and shooting nature shots, but for the mileage that I am covering, I don't like to carry along a lot of glass weights. As a result, I mostly carry my D60 with only a single zoom lens, the 28-200mm zoom (because of its wide zoom range/versatility), and I shoot subjects like butterflies and small flowers that are no more than little fingernail size.
However, at that point, I will be wanting to reach for an extension tube, which doesn't weigh much, doesn't cost much, and has no glass to get in the way of anything. I've used it to shoot subjects like "five ladybugs across".
If I were trying to specialize on one bug only, then I would change over and go for a macro lens.
When I am out in nature, I seldom have more than one minute of time to cover any one subject, so I don't like to fool around with changing lenses and taking the chance of getting dust inside my camera. I've done it, but I don't like to do that.
---Bob Gross---