Journalists need to develop their own networks to stay on top of news. Contrary to popular opinion, editors don't spend their days farming out work to reporters! Reporters are expected to generate their own story ideas and to pitch those ideas to their editors.
This means that reporters need to keep up with current events and develop their own "nose" for news. The best way to do this is to build up a personal news network which will help you stay on top of current events and breaking news and/or your assigned beat.
Success in the newsroom depends on your ability to find story ideas and sources, and sometimes it's as simple as finding local angles in national stories, or national angles in local stories.
Some types of stories can literally be seasonal. When I started out in journalism in the late 1980s, I used to look at copies from the previous year's newspapers to find out what type of stories were published at certain times of the year. That kind of research is much easier now on the web.
Paul Bradshaw talks about three key tools to building your own successful news network: RSS feeds, social networks and social bookmarks.