The deck of my high-country home is 10-year old. It was originally stained the same color as the house with a penetrating oil stain. Then, it started to fade after 1 year. This should be expected, and the stain was to be reapplied. However, the builder in honoring the warranty reapplied the stain with a different brand. This was a thicker type that coated more like a paint, and the wood was completely covered. It looked good, but started to wear out after 3 years. So, we reapplied the same type once more.
At the 7th year, disaster struck. The paint layer started peeling off. It looked awful. Yet, in places it still stuck well enough that a pressure washer could not get it off. So the deck now looks blotchy.
By researching and talking to the locals, I learned that the stain to use is a penetrating type with linseed oil. And I would not use the original brand that was used. Its rating was not that good. If I were to do it all over again, I would demand that the boards were stained on all sides, not just the top surface after they got installed.
So now, I just applied the stain to the spots where the paint has peeled. Hopefully with time, in another year or two and the old layer completely peels off, the whole surface will look uniform again.
When I redo the deck it is going to be composite. With a 1000 sq.ft. deck, it is going to cost a bit of money. A composite deck does hold the heat, but that is not a problem at 7000 ft elevation.