The Gripper in BA service was unusual in that all the First Officers were licensed in both the copilot and flight engineer seats. Typically (unless there was a training or other requirement for one pilot to be in a particular seat) the two F/Os would toss a coin to decide who sat where for the first sector and then changed seats each leg. The P3 was fully integrated into the overall flying tasks rather than "watching the gauges", and not licensed as a Flight Engineer who could carry out additional engineering tasks on turnarounds. So time as P3 was counted fully as "Copilot" hours.
With experienced crews and suitable conditions, many captains operated a leg and leg basis that meant that on a three sector day which was pretty common everyone got a takeoff and a landing in the course of the day.
You mean like this!
