Shift in focus in seasons 4 and 5

The early seasons followed a fairly predictable pattern, as others have described:

1. The paper is working on a current events story
2. Someone on staff is involved in a situation that relates to the story

However, near the end of season 4 and into season 5, there are more and more stories that have to do with the personal lives of the characters:

Billie's marriage (which takes place in season 5/episode 1 and is seldom mentioned again)
Lou's estrangement from his daughter
Mrs. Pynchon's stroke
Lou's trip to his home town

There are also a few episodes that are really more "mystery shows" than newspaper procedurals: HOLLYWOOD (season 3), VENICE (season 4), and DOUBLE-CROSS and RECKLESS (season 5) for instance,