There is only a relatively few seconds in it. Everybody I knew just reported the time displayed on Progress page giving time at waypoint, ETA next waypoint and waypoint after that. Everybody reads it off the box, and I think hardly anybody is actually aware of the difference you advise, if indeed that is the case! Course changes are not drastic on the NAT tracks, so turning time is pretty short as the FMS does control the autopilot into quite strong banks.