You've either got to find a way to make your continuing characters insteresting without making them maudlin or overwrought, or you've got to put more emphasis on the suspects.
One of the most ephemeral and important things is atmosphere and tone and it's very hard to put your finger on what creates that.
'For Unlawful Carnal Knowledge' took a year to record; that's why the playing on it might sound somewhat labored. 'Balance,' on the other hand, was written and recorded in only four months, so the whole process was quicker and more immediate.