Here is Descartes advice on reading his Principles of Philosophy, which is not bad advice for how to read any non-fiction book worth reading: "I should like the reader first of all to go quickly through the whole book like a novel, without straining attention too much or stopping at the difficulties which may be encountered. the aim should be merely to ascertain in a general way which matters I have dealt with. after this, if he finds that these matters deserve to be examined and he has the curiosity to ascertain their causes, he may read the book a second time in order to observe how the arguments follow. But if he is not always able to see this fully, or if he does not understand all the arguments, he should not give up at once. He should merely mark with a pen the places where he finds the difficulties and continue to read on to the end without a break. If he then takes up the book for the third time, I venture to think he will now find the solutions to most of the difficulties he marked before; and if any still remain, he will discover their solution on a final reading."
So, any book that is worth reading once, is worth reading three more times—with pen in hand.
There is one possibility Descartes does not entertain here, namely that he, the author, may be wrong. It's a possibility that we should not exclude, but it's also one that we should entertain only upon the third reading.
This is not to say that there are books that don't deserve a second reading. As a matter of fact, the large majority of books falls into this category.