Shoot more than you need but not more than you can afford. While taking a single frame at the decisive moment is often all you need, you cannot publish, admire or sell a photo you didn’t take.
Making an effort to shoot more gives you greater options when editing and will improve your photography in the long run by forcing your eye to develop new ways of looking at the same subject. After you take the shot that came to you easily, force yourself into different ways of composing the subject. Don’t shoot so much that you run out of space. Always bring 50% more media than you think you’ll need.