Palette Matching

[ribbits]

here's a related question, how does one know which characters to set to share palettes. \I see people who are making hacks, showing which characters they are using and which palettes they will be sharing. For instance, in Zeemis' ffiv hack (which i look forward too) i believe he has tella/rosa/edward (going from memory) all in one palette. Is that done via trial and error, or is there some planning and thought or a trick done to decide that?