I think most writers would agree that revising is an extensive and important part of the writing process.
So is deleting.
A writer must be willing to let go of words, sentences, scenes, even chapters upon recognizing that they do not work. Every word in a manuscript must forward the plot.
Now that I'm deep in the middle of my revisions, I have written, rewritten and started over on some chapters a frustrating amount of times. What motivates me is knowing eventually I will find treasure in one of those rewrites.