Anecdatally, I have two reading modes - full comprehension and skimming. In full comprehension I read and subvocalize each word, often slowing down, pausing, or even re-reading to make sure the meaning sinks in. In skim mode I look at phrases, sometimes whole sentences or even simple paragraphs, and move to the next chunk before consciously comprehending the previous one. Skimming effectiveness highly depends on my alertness level and works best with fiction or other media with low information density. For fiction books I can generally recount the plot and events pretty well.
Mostly find out what happens next faster. But on some level something about it is meditative. A constant progress across the book understanding what you can and letting everything else go. From pragmatic angle it is acquiring new information at a comfortable rate without stressful backtracking.
