I follow the lead of Black Widow, they suggest that you can leave your recurve bows strung if they are shot on a regular basis. They suggest that they be hung by the string on two level post, with the bow centered correctly. If you are not going to shoot your bow for weeks at a time, it is wiser to unstring them.
I have also been told by, Black Widow, that longbows are better unstrung unless being shot a lot. Due to the limb design, they have a tendency to lose weight if left braced(strung)for extended times.
Before I learned the longbow facts, I left my longbows strung for months without shooting them, my scales have not detected any noticed reduction in weight, but why push it. I figure that the people at Black Widow should know....