Never ever minimize the importance of timing in your life or in your photography. It can mean the difference in success and failure and the pursuit of perfect timing is what photojournalism can be all about.
Be distracted (and we all are at times) and you may miss a meaningful facial expression on your subject. Look away and miss the shot of a lifetime.
Even reacting to a situation too soon can be significant. The best example of that in our lifetime belongs to the photographers covering the Lee Harvey Oswald shooting in Dallas. When Jack Ruby fired his pistol, one photographer shot a picture almost instantly BEFORE Oswald reacted. The other, Bob Jackson of the Dallas Times Herald, shot his picture of Oswald with his face contorted in pain, a fraction of a second later, and won a Pulitzer Prize.
In sports action, a football on the finger tips of a receiver is much better than a picture without a ball, an airborne runner is better than one on the ground and when the play, be it football or any other sport, is of significance, the value of the photograph grows dramatically.
Marcus Allen had reversed his field and was sprinting toward what was then the longest TD run in Superbowl history. Take away the diving Washington player in the background and take this picture in a routine game and you have a routine picture. As it was, the photograph was in newspapers around the world the following day.
Another example of timing from the same game was punter Ray Guy catching a high snap from center. The one-handed catch and punt got the Raiders out of trouble and saved his team from giving up field position or even a potential TD.
Wildlife photography and timing go hand-in-hand as much as sports photography. Catch the eagle landing just before it touches the branch or the fawn looking at its' mother and you have better pictures than if you had taken the pictures a second later.
And always be alert! When a bird intruded on a high school football scrimmage, landing on one of those on the sideline, it was there only a second or two and then gone.
A simple pause and a "geez look at that" and the picture would have been lost forever.
For the most part, anything that adds a dimension to your picture, some emotion or action, will improve the picture.