I never use flash for editorial work, well, maybe that one time. I see editorial "photojournalism style" as fairly similar to travel work, but I've also traveled quite a bit for work and pleasure. Most of my work is in very challenging lighting situations - dark work shops, inside of boats, mid-day on the water. Not to say flash is bad, just that I've learned how to work around not having it.
First and foremost, it helps to really learn to read light. And sometimes it takes real attention to see what and where the light is, and then find a way to work with it. That doesn't always work (mid-day, middle of summer is always going to look like crap, usually).
I know people use flash quite a bit for their work, but it's just a bit too "loud" for how I work. Not that I'm pretending to be invisible, but I also don't want to draw attention to myself unnecessarily - which means "no flash".