Topbunk, on the Airbus you just enter a Z Time in the Flightplan and it will automatically sequence it and show it on the screen.
For ETOPS however, your planning for EEP and EXP uses a fixed distance generally, so it's invariant of time. As such it should be a position in space, hence the procedure to create a waypoint manually -but NOT sequence it- and view he position on he ND via ND's rotary selector on waypoints.