What’s the best Content Length for SEO & Conversion?

When you’re a blogger, you spend almost as much time worrying about content length as you do the content itself. What makes things even more complicated is that reader preferences and SEO standards change constantly. Are we still in the renaissance of the long read or are we supposed to be getting right down to it for the short attention spans of the Twitter generation? Should we be aiming for a specific word count, like a tight and tidy 500-word post or just going all out on a 2,000-word...