I've been printing up Z-ABS models with very thin walls, less than a mm, and significant overhangs. I was getting poor results with default settings. I was getting lots of stringing and irregular walls. I tried the same print using external materials settings with these settings.
extrusion temperature at 257 C
retraction distance at 1.1mm
retraction speed at 43
both sprint speed and flow rate bumped down 10%
And my print is now coming out nearly flawlessly. Still a tiny bit of stringing but nothing compared to what I was getting with the default settings. Maybe there's something going on with my thermocouple and my hot end was hotter than it should be. But in any case I wanted to share my experience in case there is anyone else out there running into similar issues. The default settings aren't necessarily ideal for every print it would seem.