You are not alone. There is so much good content that doesn't get its due simply because it's too old to make money. Until Steemit gets better at search, organizing, and archiving, I say: why not? To me, etiquette is about creating and respecting boundaries, i.e. not spamming people or doing something to harm the platform and community. In my opinion, if you've got quality content, why not bring it around again? Perhaps label it as a "repost" or "from the archive" so your followers are made aware that they may have seen it already (respecting their time). If a reader thinks a repost is or isn't worthy of upvoting, then that's their choice to click or not to click.