Some writers like critique partners, some don't. I'm one of the former, and I'm fortunate that I've found two excellent critique partners. Both of them have helped me to tighten up my writing by highlighting word or phrase repetition, overuse of passive verbs and adverbs, and showing instead of telling - some of the things that editors loathe.
But, while I've been editing based on some of their comments, I've started wondering whether it's possible to 'over-edit'. To the point where you become so concerned with technicalities that your writing loses its freshness, its spontaneity and its flow.
Ideally, I suppose you should be so aware of the 'errors' you can make when writing that you avoid them instintively. But I've always written from a 'gut-feeling' and it seems to me that sometimes you can start to over-analyse your work to the point where it becomes bland and lacking in feeling, rather than being written 'from the heart'.
I've read that 'Every word has to count, to serve the story. Any word, phrase, sentence, etc. that does not do that must be questioned.' Taken to its extreme, does that mean that you have to agonise over every single word? I think not.