With my JBLs, I started out with an equilateral triangle, but the sound with some recordings was too much left channel and right channel. Over time, I decreased the distance between the speakers by an inch or two at a time. I finally settled on the distance between the speakers being 80% of the distance to my ears. I have the speakers toed in approximately 5 degrees. So, the 83% rule is pretty close to what my ears told me was right for my application.
Since I got to this arrangement purely through experimentation, and due to the fact that I generally don’t obsess too much about these things, it actually took me about a year to get things right. I haven’t had any temptation to change things for over 2 years, so I guess I’m done.
It’s a totally different story with my Totem Arros. Those little guys disappear much easier due to their extremely narrow profile. As a result, there is a lot more flexibility in the ratio we are discussing here.
In the end, I really don’t think there is a solution that works in every situation. But then, that’s what makes all of this so much fun and sometimes even frustrating.