I've been slugging it out with some mohair recently, and in one section I had to frog some stitches 3 times
. On the bright side, in the final reknitting, the formerly frogged section looks the same as the rest -- no overuse problems, but I was extremely slow and careful with the frogging (a Zen frogging moment, I guess).
Also, after trying several joining methods, I found the the most "invisible" way to change balls (same color) was to knit with the end of the old strand and the beginning of the new strand together for a few stitches. It hardly shows. I was amazed.