Fundamentally, speed reading through something is at odds with processing that information in a useful way. And therein lies the rub: I don't read something merely for the sake of reading it.
When I read novels, I enjoy losing myself daydreaming in another world, and savouring the emotions of the characters while thinking about how I would react in their shoes. When I read technical documentation I'm attemping to create or update mental models of technical concepts. When I read a friend's Facebook post I think about what, if any, response I will offer or how I would deal with their situation. When I read a message from my girlfriend I have to take time to understand and plan for whatever she's discussing or asking.
I'm honestly struggling to see the value in speed reading. I cannot think of why I would be reading something simply for the sake of reading it without further processing. More valuable would be learning ways to process information more efficiently, i.e. accurately and quickly.