should it be treated as a one whole ETOPS "area"?
That is exactly how it is treated. Draw a "60 minute at one engine inop speed" circle around every adequate airport on a map - and this is the area that a non-ETOPS aircraft is permitted to fly in. The route that it flies - straight line, circles, wiggles etc is irrelevant provided it stays within the permitted area.
For a 90 minute ETOPS approved aircraft, you draw 90 minute circles to determine the area, 180 minutes, 180 minute circles etc. (Wind in this case in not considered, by the way)
It appears as though you are thinking that each route is approved, rather than the ETOPS approval referring to an area of permitted operations.