Family studies are almost always started with good intentions and are used to underline the upcoming Watchtower study article. Those of us who raised little ones in this religion might remember reading from the Bible Stories book - and that counted as 1 hour of study on the ol' time slip.
Most often an ongoing weekly family study ends within a month - in my experience and from observation.
Elders (these guys are rarely 'shepherds') keep track of publishers by looking at 1) their meeting attendance and 2) their monthly service report.
ginger