Every Wednesday, I have an essay on any topic that catches my fancy!
Several years ago, I remember reading an article at how the Japanese were speed-readers, consuming manga as thick as phonebook directories (the weekly manga anthologies) under an hour while riding the subway or bullet trains. Now I'm not doubting that such a feat can be accomplished. For one thing, they are comics after all and it's not like they're reading a novel. However, one thing that hasn't been pointed out is the language: that is, they're Japanese reading Japanese text. Now that distinction is quite different from say, an American reading English text. It's not simply a matter of someone reading a text in their own native language but rather the structure of their language itself.
Without going into too much detail, Japanese has three kinds of Japanese characters. Of the three, the most important distinction are Kanji characters, which in turn are drawn from Chinese Han characters. What makes Han characters difficult to learn is that they're logograms. The closest analogy I can think of that explains logograms (without sounding too technical) is that they're like symbols. For example, we have the "No Jaywalking" street sign. The street sign itself is a symbol. One option city planners could have used instead of inventing the No Jaywalking sign is to simply spell it out: N-O J-A-Y-W-A-L-K-I-N-G. But what's quicker for your brain to process, the sign or the spelled-out rule? Most people (and I hope you're one of them) would choose the former. However, the problem with symbols is that not necessarily everyone understands them. That's why we actually have driving classes, to educate and check that drivers understand the symbols used in the streets. And that quick processing is needed because when you're on the road, speed is of the essence and one doesn't always have the time to read long lines of texts (good typography also helps).
Going back to Chinese language, their entire alphabet is pretty much like that. There's lots of memorization involved but once you do memorize it, going through Chinese text is quick. And because Han characters are logograms, they also more or less conform to a certain size (compare the words "disease" and "Pneumonoultramicroscopicsilicovolcanoconiosis"--there's a distinct length difference between the two), which also explains why Chinese (and to a certain extent, Japanese) books tend to be shorter and slimmer compared to books printed in the West. (And if you're a video game geek, will also explain why the 256-character limit on the NES wasn't as much as a hindrance to the Japanese.) But that same application applies to manga. It's a quick read for the Japanese because half of what they're reading are logograms (the two other Japanese characters are katakana and hirigana but they aren't logograms).
Personally, I only noticed this phenomenon when I was watching movies with Chinese subtitles. It was quicker for me to process the Chinese subtitles compared to the English ones. Unfortunately, my Chinese is horrible, so that's not really much of an asset on my part. I'd just like to clarify that there is nothing phenomenal about the Japanese being able to read their manga quickly. It's not an issue of the comic format but rather of the language they're using.