For sheer unadulterated boredom, ASW (anti submarine warfare) exercises in the Sea King come a close second to the 727 trans Tasman freight runs. Four hours of two pilots watching fully automated transition down to an auto hover where the sonar went down to ping for subs (& subsequently a coupled transition back up to cruise at nosebleed 200ft) would often result in at least one and sometimes both drivers doing some Egyptian PT, only to be rudely awakened when the back seat broke the silence on the intercom asking for a change of position. I’d sometimes read a spotters book of ships, but that just hastened the nap time.
Even more awkward when the back seat pair went quiet and all were woken by Mother coming over the radio.