Reading is a frequent subject here and for good reason: I write and I read. You can’t do one without the other, as many authors have wisely said (including, notably, Stephen King). Douglas Wilson also offered similar advice in his tremendously helpful (and funny) book, Wordsmithy: Hot Tips for the Writing Life. His advice to aspiring writers is simple—Read a lot:
Read like a reader and not like someone cramming for a test. If you try to wring every book out like it was a washcloth full of information (and nothing but information), all you will do is slow yourself down to a useless pace. Go for total tonnage, and read like someone who will forget most of it. You have my permission to forget most of it, which may or may not be reassuring, but you will forget most of it in either case.
Most of what is shaping you in the course of your reading you will not be able to remember. The most formative years of my life were the first five, and if those years were to be evaluated on the basis of my ability to pass a test on them, the conclusion would be that nothing important happened then, which would be false. The fact that you can’t remember things doesn’t mean that you haven’t been shaped by them.
Perhaps this seems contradictory since I was recently wondering about how much is actually realistic for one person to read. And maybe it is, depending on your perspective and your purposes for reading. If you’re trying to retain all the information, you’re probably better off not reading dozens and dozens of books in a year; however, if you’re a writer, then you need to be reading constantly. Not to remember everything, but to let different voices influence your style. To see how different people write (or, depending on the subject matter you gravitate toward, which authors are using the same ghostwriters).
Writers write, but writers also read. They don’t have to remember hardly anything of what they read, but they need to do it.