Deck Paint Questions

[MDarrough]

I have a two story house with a deck off each floor. They are both the full width of the house (50 ft) and run out 10 ft from the house. They're in full sun most of the day and I'm getting tired of repainting every two years. The part that is under cover is in a little better shape, but still needs repainted. I have been using Sherwin Williams deck paint.

So for all you deck pros, here's a couple questions for you:
1- Am I expecting too much out of deck paint to last more than 2 years?
2- What is the best paint to use in my situation?

Thanks for your help!!

Mark