Many reading experts advise us to go slower. According to Maryanne Wolf, the developmental psychologist and author of Proust and the Squid: The Story and Science of the Reading Brain, deep reading is indistinguishable from deep thinking. The corollary is that superficial reading engenders shallow thoughts.
To be sure, scanning texts quickly without sacrificing comprehension is an essential skill. (I’m forever grateful for having learned speed-reading in middle school.) The smart choice is to ex both sets of muscles, fast and slow, exercising the latter instead of letting it atrophy.