What is the most effective way to publish as much of your PhD thesis as you can? Is it to try to summarize many chapters in one article, or you would try to publish standalone articles for each chapter?
I'm in Philosophy in the UK.
I have read that one should not try to squeeze an entire thesis into an article. In my case I have already published the long introductory chapter, so what's left are a list of criteria, case studies, and a conclusion.
This depends on the dissertation and the field. Publishers want to publish significant results, not chapters. If you have several independently important results you can publish a lot of papers. If you have a dissertation with many results building to a main result, then maybe yes or maybe no, depending on the importance of those intermediate results. 

But it is up to the editors and reviewers to make a judgement about publishing. 

In some cases, a journal will be willing to publish a long article that contains all of your important results in a single paper. This gets the essence out without trying to salami slice the dissertation.