We put our efforts into writing daily posts on Hive to keep a pipeline of new content that gets rewarded over seven days. However, even content that is older than seven days has value. Although our curation of old posts may not generate any Hive, we can still make comments, which are fresh content.
Old posts are great for comments and comment curation, assuming the post is interesting enough to inspire more discussion.
With this in mind, it would not hurt to repost older content for the sake of continuing a conversation.
At the very least, Peakd gives us the option to tip the content creator once a post has gone past its curation window. In this respect, an old post can still be worth something to the creator and the person giving the tip.
With this in mind, don't stop yourself from exploring old posts and commenting on them. You may find some great content that you missed when it was fresh; but, you can still reward the author.