Ditto to Dave: wash rods and reels with fresh water immediately after use in salt water, and back off drags on all reels, salt and fresh of any size. I read this bit about backing off drags many years ago, and Mike at Mike's reel repair advised me years ago to do that. Mike and I were talking about salmon sized reels, however. (He also told me how to loosen a newly replaced drag on a Daiwa Sealine that was a bit tight: "Go over to the river and hook a big Chinook and let him burn in the drag with a big run.")
I've never had troubler with a drag whether I remember to back it off for the winter or not.
On a tangent: I ruined a brand new medium sized spinning reel with one trip to fish salmon from my kayak in salt water, even though I rinsed it in fresh water after fishing. Salt water ate up its gears and internals. It still works, barely, but makes an awful grinding noise when turned. Since then, when I buy any reel I MIGHT use in salt water I make sure that it is designed for salt water. My current favorite steelhead reel is a medium sized Cabela's Salt Striker and I use it interchangeably in salt water or fresh.
