We witnessed the Defiant
get destroyed in deep space far away from other assets - supposedly on a mission similar to Kirk's. The Exeter
was found, apparently by accident, by Kirk during one of his missions to space not frequented by UFP travelers; the Constellation
If anything, we might deduce that ships of this class perform near-identical missions, and moreover that these missions overlap: one month, a region of space might be explored/patrolled by the Enterprise
, while the next month, the same space might be covered by the Constellation
(as "Doomsday Machine" would have us believe), and a region previously studied by the Exeter
would later be given a second look by the Enterprise
(as "Omega Glory" suggests).
Starfleet might do wisely to build a dedicated ship class for these missions, so that it wouldn't have to take any dedicated warships off the hot spots on the border, or any dedicated geological survey vessels from years-long missions of fully mapping a planet's mineral riches. Essentially, the Constitution
would be a jack-of-all-trades ship for frontier purposes, quite possibly inferior to other dedicated designs in every single field but superior in combination. Or then it's actually an ace-of-all-trades, overengineered at great cost to do everything and thus to waste most of its capabilities at any given mission - but so that Starfleet doesn't need to send another ship to the frontier to do the job every time a job is specified.
If the previous incarnations of Trek and the latest two movies are to be taken as representing one and the same universe, we might do well to choose to believe that the Constitution
was at most a jack-of-all-trades midget vessel, and perhaps just a deuce-of-all-trades in relative strength. A Constitution
skipper would still be the cream of the cream, in major part for performing heroics with such a crappy little ship...