I'm the social media designer for the company I work at, and most of our images are just used for posts. I've been asked to follow the 20% rule and have even been asked once or twice to make the text smaller.
Is this a rule I should be following if the images aren't ads? I've even used the text overlay tool to see what Facebook thinks of the images and received an image text: low score. Not the highest score, mind you, but the second best.