While every writer has their own particular process they follow, one finds almost universal* agreement on one thing: It's good to put your manuscript aside after finishing that first draft, let it stew for a bit, and come back to it 6 or 8 weeks or so later and read it again with 'fresh eyes.'
Yet even with a long break, I find the very act of re-reading one of my manuscripts triggers my memory, and while I occasionally surprise myself ("Wow, that scene worked even better than I thought!"), more often than not, I don't. I anticipate the words, recognize the sentences, and find myself reading something on page 38 that I know I have almost word for word somewhere later in the story—and I almost always know exactly where to find it. This makes it harder to properly edit the story, because I know what I meant to say and thus I'm not always the best judge of whether I've said it right.
Interestingly enough, it doesn't work quite the same way when I re-read someone else's work. Last week, a friend handed me a copy of Richard Russo's Empire Falls, thinking I might like to read it. She's right--I read it about two years ago and liked it quite a bit. As I found myself between books with nothing new handy, I picked it up and started reading it over. While it's familiar, and I know how it will end, and pretty much everything that comes in between, it's not stale for me. More interestingly, I'm not anticipating sentences or words, or skimming over bits or plugging things in ahead of time.
Even books I've read a lot—Salem's Lot, The Lord of the Rings, A Prayer for Owen Meany—don't 'burn in' the same way. These are three books I pull off the shelf every few years and read over again, and they're familiar, yes, but they don't trigger the same anticipation of something I've written. I suspect it's because I've only ever read the book. On the other hand, something I've written, even if I haven't looked at it or thought about it in five years, is not something I've merely read, it's also something I functionally lived with for a period of time. It was in my head, front room and back, was part of my life for a while in a way that something I've 'just' read can not be. It's burned in my memory banks, the way you can burn in an image on your computer monitor or TV screen if you leave it on too long to the same thing.
*almost universal. While there are those who don't do this, they seem far outnumbered.