With the Facebook 20 percent rule, what Facebook aims to do is to control the quality of images that get posted to the site. This means you won’t be able to get away with posting images that are spammy in nature – or misleading (which is a good thing). So how is the new Facebook 20 percent rule going to help you?
http://www.christiankonline.com/facebook-20-percent-cover-photo-rule/

