This seems common sense to me. Any skilled reader knows when to skim and when to read. The most important thing in reading is to avoid sub-vocalization which slows us down. (In fact, in conducted my own informal study on the Boston "T," I am amazed how many people "vocalize" while reading. It's like they are whispering to themselves.) "Reading silently is faster for skilled readers than either reading aloud or hearing someone else read the text. This difference reflects, in part, limitations on how quickly we can talk. A speaking rate of 150 to 160 wpm is comfortable; this is the rate that is recommended for speakers who are recording audiobooks or podcasts."
Rapid eye movement, something on which speed reading concentrates, is less important. In fact, real understanding presupposes the ability to be able to go back in the text, sometimes a whole paragraph or a whole page. Indeed, the advantage of normal reading over speed reading that it does not "force the eyes to move straight down a page or present words one at a time is this opportunity—the opportunity to move backward in the text in order to recover information that was initially missed or forgotten." To sum up: "although immediate comprehension may be successful with single sentences presented using RSVP speeds well beyond typical reading rates, scaling up to full text passages yields substantial comprehension costs."
This does not mean that using a pencil as a guide may not be useful, but it does mean that the exaggerated claims for speed reading are false. "Speed reading" is closer to skimming than to reading, or so it would seem to me. In any case, there
is a trade-off between speed and accuracy in reading, as there is in all forms of behavior. Increasing the speed with which you encounter words, therefore, has consequences for how well you understand and remember the text. In some scenarios, it is tolerable and even advisable to accept a decrease in comprehension in exchange for an increase in speed. This may occur, for example, if you already know a lot about the material and you are skimming through it to seek a specific piece of information. In many other situations, however, it will be necessary to slow down to a normal pace in order to achieve good comprehension. Moreover, you may need to reread parts of the text to ensure a proper understanding of what was written. Bear in mind, however, that a normal pace for most readers is 200 to 400 wpm. This is faster than we normally gain information through listening, and pretty good for most purposes.
The article and the study are well worth reading for anybody interested in taking notes properly.
1. See also here.