I should mention one more possibility before closing, one that I've used myself on a couple of occasions.If you watch old seafaring movies you've seen this one too.Teak decks can be scrubbed periodically with sea water and a stiff brush and will actually last about the same length of time as an oiled deck.

The main drawback to this is that without any protection the wood will absorb everything which is spilled on it, and many modern oils and greases, to say nothing of not so modern wines and berries will leave stains which will be just about imposable to remove.On the  other hand if you have a lot of teak on your boat you could likely write a book with the time you would save by not having to keep up the varnish.

Whatever you decide, may all of your boating adventures be happy ones.