I've noticed the same patterns you've described in your story, especially the 5-minute mark being the sweet spot.
Thank you for sharing insights into paragraph lengths. I wasn't aware of that, but it makes sense - since they're trying to avoid long text-walls.
I think you did a great job sharing insights, but you may want to expand on some points to get to the 5-minute mark...just kidding!
Thank you for the insights, and Thank you for sharing!