One problem I have had with speed reading techniques is a difficulty in adapating to the wide variety of reading habits one may employ.

I speed read both research papers and novels, but in very different ways. With research papers I browse and download many, skim abstracts, jump into the middle of papers, usually look first at the pictures, then eventually start reading paragraphs. I usually can 'get' the paper's key concepts without having to read most of the text, although it depends heavily on the type of paper.

When reading a novel, I usually alternate between full reading for important/interesting portions and skip reading for boring or fluffier parts. I typically skip long visual descriptions (I find that whatever visual imagery I randomly summon usually works just about as well). When skip-reading, I typically scan the upper left corner of a paragraph and it's first sentence to decide if I want to skip it. I rarely spend more than a day or two on a novel. If it is really unusually good I will spend more time with it.

I have yet to find more advanced techniques that actually allow me to read dense material at higher speeds. The simpler level-of-detail control is effective enough and doesn't sacrifice comprehension for important material.