There are almost as many reasons to perform a go-around as there are airplanes at your flight school: a bad approach; another airplane (or vehicle, or animal) on the runway; you can’t hold the centerline on a crosswind landing; you’re caught in a porpoise or a balloon. For these reasons and many others, it’s best to keep a go-around at the ready. Practice go-arounds often so there’s no hesitation when the need arises.