If you have a wood deck in Santa Cruz County, it is highly recommended  to have your deck maintained annually.  If there was one question that was asked more than other question as it pertains to maintenance, it is whether or not the rails need to be maintained annually.  I usually answer that by saying NO, however the top 2×6 that caps the railing should definitely be maintained as often as the deck itself.  Basically, if the board sits horizontally, it weathers much, much quicker than any vertical board.  This picture of a railing in Pasatiempo best exemplifies that.  We came back to this deck after two years, and all the vertical posts were still handling stain quite well, yet the top piece was obviously in need of a cleaning and some more Biowash Natural Deck Oil.