When I was in VP-6 you had three officers on board. The PPC, or Patrol Plane Commander, a Co-pilot, and a Navigator (who was also a qualified pilot.) All of the officers wanted to be in the front seats flying the aircraft. The job of Navigator was not popular, so it normally fell to the most junior pilot. Back then, you got to be a PPC by accumulating enough "stick time" (flying time in the cockpit). If you were the junior officer on a crew, you were at the mercy of the more senior pilots if you wanted any time in the cockpit. You could also get time in the seat if it were listed specifically on the flight schedule.  

Or the Navigator could get stick time this way:

 I was in a crew that was flying north out of Midway Island. So far north, that the pilot thought that navigating on this trip was very important. Our mission was to take us far enough away from Midway Island that when our co-pilot asked the PPC "What do we do if we lose a engine?" the PPC said "we will try to make Adak" in Alaska. Any way, when we finally flew out of range of the TACAN on Midway, the pilot came back and asked our young officer Navigator, "Where are we?". The young Navigator drew about an 800 mile circle on his chart and said "we are in there". The next thing I knew, the Navigator was in the left seat and the PPC was doing the navigating. I always figured this young officer was not a good Navigator, but he was smarter than we thought because he made PPC real fast.