“By seeking and blundering we learn” Johann Wolfgang von Goethe said. There’s no better way to learn than by making mistakes.
I believe this to be especially the case in creative writing. I’m not saying we should publish something that has errors in it. Once you’re ready to publish your story it should be the best version it can be.
I’m saying that as your story is progressing re-writing and asking feedback is vital. It can be frustrating, but it is a great way to develop your own skills. Practice is key and practice also indicates making mistakes (otherwise we wouldn’t call it practice, now would we?).
This may mean already written chapters have to be cut. It may even result into starting a story all over again. And that hurts, no matter how often you’ve done it. Yet if the outcome is a better manuscript and a publishable story that you feel proud of, it’s all been worth it.