Topic: Somebody please explain this chart

[Brian Skalinder]

So, what exactly am I supposed to be trying to achieve? Please don't say, "do whatever sounds good to you" or "there's no right or wrong answer." While there may be more than one right answer, there are definitely wrong answers or you are all wasting your time here.

While there may be wrong answers, those are pretty obvious (e.g. don't arrange your stereo pair of cardioid mics both pointing precisely 180º away from the sound source).  The vast array of "right" choices really comes down to what you're trying to accomplish.  I know it's not the answer you want to hear, but the goal for most of us is to come home with a recording we enjoy personally, hence the suggestion to use mic configurations that sound best to our own ears (using our own playback systems / environments).

There's a continuum of angles and distances that can theoretically produce the same result.

I wouldn't say same.  As Gutbucket points out in another thread linked in the stickied post previously referenced:

The Stereo Zoom is really about optimizing only one aspects [sic] of recording, namely getting the stereo-ness accurate.

So while two configurations having the same stereophonic recording angle (SRA) may produce the same "stereo-ness", they won't produce the same result.  For example, using cardioids, both 23cm / 120º and 50cm / 20º have an SRA of ±40º.  But 23cm / 120º will pick up much more reverberant and ambient sound, while 50cm / 20º will pick up less reverberant and ambient sound.  So it's important to take into account other factors, aside from just "stereo-ness", as Gutbucket also notes:

There are other things to consider that are often more important such as the frequency balance at the mic position, clarity, the direct-to-reverberant ratio, the off-axis performance of your microphones, blathering drunks, the balcony overhang, the noisy bar on your left, the raucous mosh pit, the sqeaky chair where the guy that snores always sits, the HVAC exhaust that blows on your mics, etc.

And finally, a nice summary here:

The Stereo Zoom is a great tool, the trick is to understand the ideas behind it so you can decide when and how it is best applied, also realizing that there might be an better tool to do the job in some cases.

One of the challenges for a lot of concert taping is minimizing reverberant / ambient sound (e.g. in venues with cruddy acoustics, obnoxiously chatty crowds, etc.).  In this context, one of the big ideas to take away from SZ is that if you know the SRA (i.e. the degree of "stereo-ness") you like, then to minimize reverberant and ambient sound select a mic configuration with the desired SRA that captures the greatest degree of on-axis sound from the source.  This typically means using a configuration that has a narrower included angle and wider spacing.  The narrower the included angle, the more on-axis your directional mics are with the sound source, the less off-axis -- i.e. reverberant and ambient -- sound they'll pick up.  Just one example of factors to consider when selecting a configuration.