If your going to stay in the home for five years rip it out and rebuild with a synthetic such as Trex. For any exterior wood that doesn't get walked on finish with One Time Wood. You've got better things to do and spend money and time on than strpping,cleaning,conditioning treating wood every year or two.
Jim
With oil finishes, a year to two is about all you can expect. The upside to oil, is that you can recoat very easily, with little chance of making a peeling mess. I used oil on my kid's playground around 4 years ago, and it's about due for a recoat.
The water based finishes above should easily last 5 years or more. But you can't just recoat over them, and you can't just apply them to wood that has been treated already, or it becomes peeling mess time. I used water based stain on the underside of the roof over the same playground (the top side got paint). Since it isn't in the sun, it still literally looks like new.
Still, there's much to be said for real wood. With three or four refinishing sessions over a 20 year lifetime, wood can be very economical.
As for "One Time Wood" vinyl type decking, it isn't all its cracked up to be. My in-laws had a deck replaced by TimberTech. The beautiful brown deck was so grey it was nearly white after two years. That was a couple of years ago, and it's well on its way back to that point again. The brown Azek railing is only brown where it is in the shade.
Aside from fading, it can get awfully hot in the sun if you like to walk around barefoot, and it is just plain awfully expensive. Plus, many of the less expensive vinyl decks are made to be put on 12" OC joists, and feel springy if decked over a 16" OC frame.