Correct. However, my point was that there are some NW fare classes like Q that yield 100% EQM on a NW coded but CO operated flight, but often equate to 50% EQM fare classes on the CO side. You can verify this by looking at the reservation on continental.com. So you can theoretically book a CO flight via NW and get 100% EQM for less than you would have had to pay CO to get the 100% EQM. Whether there are many actual opportunities to do this I have no idea.

It works the other way too. I booked a trip on CO that had a NW segment. It was booked as a CO codeshare with an H fare (150% EQM). But NW showed it as an M fare (only 100% EQM). In the end it was treated as a CO H fare and I got the 150% EQM.