I used another analytics tool before that had the scroll-depth as part of reporting. This was very useful, since I have long pages. The max-amount of scrolling is a good indicator how your page/article is valued.
Screenshot of the other tool below. I can imagine it being a metric next to bounce rate. With filtering Pirsch provides (I love how this works) the number can be specified for different pages.
I never thought about this type of measurement. The drawback I see is that page length could be relative, as it‘s prone to changes, especially if the content is regularly updated. But nevertheless, it‘s a cool thing to have.
