Which again makes this five-year thing sort of nonsensical, because the missions of exploration are two weeks long only - either thanks to technology, or thanks to the fundamental nature of warp propulsion. Why tie down Kirk and his starship for years at an end when anybody can hop to the final frontier at a moment's notice and be back before the commercial break ends?
We could say the Enterprise
was one of those ships that were part of an exploration pool - in a policy decision, they could be summoned from their more important duties to exploration errands, while other ships could not. For the Enterprise
, this exploration alert status was to last for five years, and several sorties were indeed made.
But that is completely at odds with Kirk actually having been five years out there, or with the ship having five years' worth of supplies, or whatever other arguments have been made here...