They say variety is the spice of life and when it comes to photography, this is certainly true.
With film there is a financial advantage (superficially) to being frugal in our shooting. Film and processing costs money we may not want to spend. But with digital photography there are no such financial benefits from being frugal. Memory cards are fairly cheap and can be reused over again. Portable disk units that will download your pictures in the field are available which minimize the need for extra memory cards. And sometimes having a laptop with you in the field is a great idea.
You can never predict in advance exactly how you will use an image. Your images can be a resource well into the future and what will you be using your images for in 20 years time? Can any of us know?
It thus pays to shoot a great variety of shots of each subject you find. Verticals, horizontals, wider shots as well as details are all great to take. In basic photography courses we were taught to crop in camera, but this was in the days of film, and especially transparency film, where there was little opportunity to work on an image later. But with digital, working on an image is natural, so having a wide variety of shots is hugely useful.
Let me give you one practical example. When I was editing Digital Photography & Design magazine we were always looking for cover images. Readers would send in great cover images that were cropped tight in camera with the subject filling the frame. However magazine covers typically need space for the magazine title and for the all so important cover lines that promote what is in the issue and attract potential readers. It was sad how many times we would find a great image sent in but with too much of the scene busy with the main subject. We would contact the photographer and ask for a wider shot and guess what, they would not have it. They had cropped in camera and only taken that single shot. Or they had send in a landscape shot (a horizontal) and we naturally needed a vertical, yet because of the shot could not adequately crop one from the supplied (and usually only) image.
So if you view your photographs as a resource that you may use over an extended period and in many ways, you will benefit from shooting a variety.