I'm sure this question must have been asked before, but... In TMP, the Enterprise (which is undergoing a refit) is the only starship within three days of Earth as V'ger approaches. In TWOK, the Enterprise (which is being used as a training vessel) is the only ship in the quadrant with Regula I (presumably near Earth, as the Enterprise has just left spacedock). This suggests that although Earth is the capital of the United Federation of Planets and the location of Starfleet Headquarters, they don't routinely keep an active-duty starship anywhere nearby to defend it. Yet Starfleet happily sent three starships for strictly ceremonial purposes to the inauguration for the president of Altair VI. What is up with their priorities?