We aren't required to do this on the 767, it is in the FOM for the Whale. The light twin PIC circles and signs on the release and we go under 121.483. There are no sleeping facilities on the 767, and there is no transfer of PIC authority while underway. The FO who keeps the left seat warm while the PIC is "on break" is not the "Relief PIC".

For the 744, reference 121.485(a) for flights greater than 12 hours: They are required to have a sleeping facility and that's why they get to do the extra work on the OFP.