I came to know many readers of English books and they are roughly divided into two groups.
One group is made up of those people who start to read English book out of sheer desire. They usually have some particular books in mind which happened to be written in English. They're desperate to read those books even in English that they decide to learn English more and read lots of books. As a result of passionate and pleasure reading, they become a fluent user of English.
Here are some comments my friends said after reading long fanfiction stories with PC「読み終えたころには首は痛いし目はチカチカしました」「長編を読んで2週間ぐらいモニタの前でがんばりましたが、終わった頃にはめまいがしました」See? It's very costly to read published English books all the time, so they look for an easier way and read free fanfic stories. But without an ebook reader, it used to be a great hassle to read them. There was no options besides reading them on PC. You've got to stare into the screen for many many hours.
Now, the other group. People in other group are doing the same, reading English books, but they're i a way totally different. Their primary goals of reading English books is to be a good user of English. They want to be good at using English. Along the way they look for an effective approach to be one, they come across tadoku and start to read lots of books.
Then, what happens to the people who belong to the latter group? Do they all become a good user of English. I'm afraid many seem to remain a learner of English and forever grumble saying they can't understand English well or they can't read books fast enough. Only few are lucky enough to come to experience the sheer enjoyment of reading books, whatever language the books are written, and grow into a beginner of using English.
English is a subject you have to study at least for three years as compulsory education in Junior high school in Japan, but I'm often urged to saying that you should stop learning English and do some other more easy and enjoyable pastimes if there is no particular reason you have to learn English. Without passion, nothing will be gained.