"...the taking of opportunities as and when they arise" is a key part of great photography and one that is difficult to practice. Some opportunities are obvious but others require enough knowledge of the elements of a situation so that the shooter can anticipate some possibilities and be ready for them. A simple example is the shot below of David Toms at the 2011 Zurich Classic. He's on the tee box. I'm already in burst mode, quiet shooting, long lens, press and hold the shutter button. I don't enter contests but I often look at their results. I'll see a great shot of something and know that what the photographer accomplished was a reaction with camera settings and composition that captured not just the action but also the moment.
David Toms, 2011 Zuruich Classic