Without data, you have a few choices:
- follow the IOLM
- follow your gut
- follow someone else's gut
After all, if you're going to eschew real data driven decisions, where's the harm in SWAGs? Pick any one of those three choices; none will be proven better or worse than the other.
What engine? Is it the turbo v6? I'd venture you might find UOA's on here of vehicles with the same engine in an Expedition or some other vehicle. Otherwise, I'd personally just follow close to what the computer or manual say.
If you trade your cars in every so often, then you can follow the OLM. If you plan to give your Expedition a "forever home", then I would do 5k changes max.
If it is the tiny V6 ecoboost and you two anything twice a moth, I would do 5k OCI. It is a very expensive truck and oil is cheap. If you change your own oil and like doing it, just get Kirkland oil and change it every 5k regardless of use.
3.5 ECO's do well with 5k OCI's. If mine, that is what I would do. Quality 5-30 synthetic with a quality filter. If I wanted a bit longer OCI I would likey look at Mobil 1 0-40 and do a run of 7K and a UOA to see where my engine was at and go from there.