Note that the current Subaru recommended oil change intervals is not necessarily what is in your original owners manual. The screenshot above looks to be taken from subaru usa recently. The fine print says that for totally normal driving, you can change oil every 7500 miles or 6 months in the non-turbo engine. But the list of things that constitute severe service and thus, 3750 oci is long and includes city driving, frequent starts and stops, short distances etc.
So practically, the conservative rec is 3750, or every six months.
Now, if the engine does not leak oil, does not burn much oil and lets say, you average 8,500 miles per year, then I would have no fear at all going every six months (and thus every 4,250 miles more or less, for instance).
And, should you really hate changing oil, or perhaps have environmental considerations, then the whole discussion of using full sythetic, extended oil change oils, like Mobile 1 12,000 opens up. I am going that route in my newer Prius, but scared to consider that long an OCI in an old Foz.