Afraid you are very wrong Andyy, Seamen Officer has been out of existence for years and years. Pilots and Obs are indeed Warfare Officers, but unless they have a Bridge Watchkeeping Qual they are as much use as a YO (albeit vastly more experienced) and therefore do not keep watches on the bridge unless they volunteer. In addition, only having 1 P and 1 O on board (unless a P2 or O2 are gaining experience with that Flight), means that to try and stay within credible limits for rest and fatigue coupled with about 8 secondary duties each results in a shortage of time that would certainly not be helped by standing a 4 hr watch on the bridge for which they are not qualified or embarked for that purpose.