From three to ten colors are used to create these colorways. No color rules or theory here--anything goes. I was never a big fan of coloring in the lines, so you will find that wherever two colors meet there is intermingling. This is where the true color magic happens.
Some colorways have more frequent changes in them than others. This is visible in the skein photo. The bigger the band of color, the longer the repeat. There are some that stay in the same color family (as in Nodding Violet) and some that are all over the spectrum (as in Fire on the Mountain). A lot of these colorways were created for sock knitting, but they are certainly not limited to that.