Another thing to bear in mind:

EUA's on "direct" (i.e. onestop) flights are especially difficult. In order for them to happen, there must be open F seats on both legs. In order to get a seat assignment, IIRC the SAME seat must be open on both legs.

I was on the 753 ANC-SEA-IAH in January as part of a MR. The GA at ANC was kind enough to break some elite itineraries into two separate segments, hoping to get a few people upgraded for ANC-SEA, knowing that SEA-IAH is in the not-quite-as-hopeless-as-a-transcon category for upgrade purposes.

As a lowly Silver, I saw zero upgrades, not that I was expecting one. Since I opted not to get off the plane at SEA, I spent a LONG time in a LONG tube!

All that to say, your upgrade chances are at least somewhat better on a nonstop or connecting itinerary than on a one-stop, same flight number/same plane itinerary.