I am a big fan of Rand Fishkin from SparkToro, and this method for creating viral content is genius, check it out.
A content audit is something that I recommend doing around once a year to help you evaluate your content so you find any areas of opportunity, and also to make sure that you are still ranking where you need to be. If you are wondering, "what's a content audit and do I need to do one?" then this guide from Ahrefs is for you.
Why is this the case? And what can you do about it?