Don't look back, Satchel Paige is reputed to have said, because there might be something there ... and it might be gaining on you ...
Too much time looking over one's shoulder, you can walk smack into a wall in front of you. Nostalgia is nice, but be-in-the-moment is the way to go most of the time.
Having said that, now and again, I pick up a book I have read before and re-read it. Sometimes, the book is one I have written. Not often, but now and again, I do find it instructive.
Mostly, by the time a novel I've written is published, I have read it four or five times: First draft and maybe a rewrite. Again when I get the copy-edited ms back from the editor. Then, the unbound galleys, and finally, the finished product. These are all working reads -- to correct errors -- mine, the editor or copy editor's, the printer's. Once the thing hits the racks, I'm tired of the sucker and I'm done. A copy goes onto my ego shelf, and I move on.
After some years, I now and then get the urge to pick up one of my literary children. My expectation is that I will cringe at the writing and story-telling, having -- I fancy -- gotten to be a better writer.
I was on a panel with Ursula LeGuin not too long ago, and somebody raised those questions: Do you ever re-read your old stuff, and if so, does it make you wince? Ursula's response was pretty much how I felt: Actually, no. I'm usually surprised at how good it is.
It's almost as if somebody else wrote it, and it's the kind of book I'd like to read if they had.
This is not to say that they all stand up well, nor that you can't see the brush-strokes, so you do tend to realize what you were thinking when you wrote a particular scene, but enough time, and you forget enough of a story so that parts of it are something of a surprise. Huh. I had forgotten all that romantic by-play between Toni and Alex, the rocky aspects of their relationship, the temptations. Gee, I didn't remember that I had two soliders use the word "fuck" twelve times on one page. Wow, that's a great descriptive metaphor -- how did I come up with that?
The ego rears: Damn, I'm good!
In Desiderata, Max Ehrmann has this line: "Keep interested in your own career, however humble; it is a real possession in the changing fortunes of time."