3 years and 15k miles is EASILY within their capability, presuming all mechanical conditions are in good shape.
I have a few vehicles that see multi-year OCIs; never ever had a problem with a filter for 3 years. Nor the oil, for that matter.
The whole ".... or one year ..." oil and filter change mantra is predicated on the product supplier taking an ultra-conservative approach to limiting warranty for the purpose of protecting their liability exposure. It has NOTHING to do with watching out for you. If they didn't place a limit on the warranty, then by definition, the warranty would be "limitless" and you could use their product indefinitely. Hence, they pick an arbitrary limit that well suits their proverbial CYA mantra and don't worry about what we have to spend.
I fully understand that "oil and filters are cheap". That is a "cheap insurance" mentality. And in the absence of facts and data, it makes sense. Read that again - in the ABSENCE of other information, it's a fail-safe conditional response.
But those of us who do extended OCIs and FCIs, and track UOA and PC data, pull valve covers for inspections, do compression checks, and investigate filters with autopsies, can assure you that multi-year changes are perfectly safe and doable, as long as your equipment is in good mechanical condition. We use data, not dogma, to manage our equipment.
So, if you're not into making your own decisions on data and facts, and would rather stick to OEM (corporate predicated self-protective) mantra, then by all means, dump synthetics and premium filters every 5k miles ... because that methodology is only "cheap insurance" in the absence of good information.
And I can understand why some folks do that. They are not interested in popping off valve covers, or messing around with UOAs, or cutting messy filters apart. OK - I get that. Fine by me. In that vain, "cheap insurance" probably is a quick/easy O/FCI swap. But if you are going to follow that maintenance program, then why waste premium products such as syns and high-end filters? There is zero proof that these products protect any "better" in a normal OCI pattern. So why install, and then throw away, products that excel in extended OCIs? There is no "cheap insurance" to using a premium product where a normal product is perfectly capable.
So you have a few choices:
1) use premium products, and greatly extend the OIC/FCI and seek a decent ROI while providing good wear protection
2) use normal products, and OCI annually; there will be a moderate amount of waste but protection will still be fine
3) use premium products, and OCI annually; there will be a huge amount of waste, with no gain in protection over the lesser cost alternative