Amazing what can be cut

I've been working on building a website about myself and the book (to be announced here when it's finished), and one thing I did today was to pull out some pages of my book for an excerpt to include on the site. As I was looking it over, I was amazed at how much I kept finding to tighten it. This was an excerpt of about 750 words, a key moment that establishes some of the basic drama to kick off the story, written early in the process and revised a thousand times since then. And I found about 6 different phrases and half sentences that I now recognize as clutter but somehow never did before. At what point do I trust that I've caught everything that I'm capable of catching and call it done?

One lesson of this exercise is the benefit of reading in short bursts. I think if I had read and edited this section and kept going for a couple of hours, I would have found less and less to cut as I went on. It's really hard to get in and stay in the editing mindset when you're feeling hurried -- when you're thinking less about how it actually reads than how much you want to get it done.