They say: You should never, ever re-read what you've written while you're working on your writing project. Leave all revisions until you finish your first draft.
I strongly disagree. But was willing to refrain from commenting. That was until I encountered this advice blazing through out the Internet like a wild fire. Then I just had to cry out in protest.
I choose to protest not simply because I disagree but also because I don't believe anyone has the right to dictate how someone else should work.
There are a few rules we--as writers--must follow (grammar, spelling, etc.). But how you work should be left up to you. What works for you--works for you.
Advocates of "no revisions until the end of the first draft" insist that if you break this commandment you won't get anything written--of course.
Yet, me--the breaker of said rule--has completed three book-length manuscripts since 2011 (plus short stories and articles).
Do I read the entire manuscript at the beginning of each writing session?
Here's my strategy...
At the end of each writing session, I highlight the unsatisfactory passage in red.
At the beginning of each writing session, I re-read the chapter containing the unsatisfactory passage. This is where I start working.
Advantage of this strategy...
It ensures consistency of story and voice.
It gives me an easy in to start working on the story.
It saves time. Yes, that's right, it saves time.
So, do I demand that you should make revisions as you write?
Nope. Freedom is the word.
Try editing while you work. If it works for you, do it. If not. Don't.