Yes, 4 years ago. I had been working some temp jobs and this job came up just as my other temp job was finishing. It started as a temp going to permanent at 8 weeks in. I walked out 6 weeks in. There was a huge culture of bullying, bitching and backbiting and the systems were not up to doing the job that needed doing. I had spoken to my line manager and eventually the boss of the office area I worked in. I had lots of promises of things being dealt with and changed etc but nothing ever happened. I walked out one early Wednesday afternoon after telling the boss I was leaving and not coming back. He was really shocked but as I explained to him that I had given the job a reasonable chance and spoken to them about the issues I was encountering but nothing was resolved despite promises to do so.
I started a new temp job the Monday after, my agency was behind me all the way and decided to drop the company I walked out from as it had happened before with other temps, I wasn't best pleased when they told me that after the fact and asked them not to send anything my way like that again.
It was absolutely the best thing I could have done in that situation, the last week or so there I was in tears before, during and after work and I knew it wasn't sustainable. The 'big boss' of the company called me about a week after asking if I would reconsider and go back, I thanked him but declined his offer.