Say you were flying from Oxnard to Watsonville, in California. You would take the V-25 airway part way, entering in Santa Barbara, exiting Salinas; the route doesn't, by any means, have to follow the airway for its entirety, only small portions. Now, an aircraft needs not exit an airway at an interesection, most especially when there is no exit near the airport. Not all routes need to be on an airway anyways, flightplans plan out any number of waypoints that the aircraft flies to on its route, whether it be on an airway or not. The airway is meant as a means of organizing flights so that the airspace at said altitudes aren't crowded; they aren't necessary at all times. Remember, each day a flightplan may be different, depending on teh wind, and other weather conditions, airways may take one over airspace that permission to fly over isn't there one day, and means are meant to move around that.