I own screenprint separator. It does have value for those who regularly use indexed separations in that it automatically exports your indexed files from Photoshop so they may be printed out and/or modified using Illustrator. However, I
never use the standard palette or clut (color look up table in sps). To get a decent accurate reproduction of a design selecting your colors manually is the only way to go. Small changes make a big difference! Auto programs don't work well in 4cp nor indexing unless the design is very simple.
That jimyo tut taught me the most about indexing.
In my experience I do get quite a bit of mixing due to initial ink stacks getting smushed by subsequent screens. Since I've always had to make some compromises in my sep to deal with the limited palette I often look to print order and flash order to help get a better print. No matter how long I look at print order, it always seems that I find myself adjusting the print order after test prints are made. I often find myself printing a group of light colors first, a flash and then hitting some of the darker colors after that. Darker colors usually go first, but if they are fine details that are getting swallowed up they have to move in the print order. When printing skin tones with a lot of contrast across the subject I'll often hit the light "flesh" tone and the darker "redskin" color early in the print order and not flash them so they blend much better. Even my highlight white gets moved up if it is just too intrusive at the end. Print order is big when indexing.
Since I print on a manual, I do longer runs and I desire consistent results indexing works very well for me.
185 ppi, white underbase, black, highlight white and 4 custom colors through 230 mesh (the black shows up better on the shirt than it does in this JPG)