A common error is to not keep track of the lengths of the rod sections on the finished rod - that is if you want to consider it to be so. Coming from Bamboo rodmaking, I'm obsessed that the various sectons of the finished rod should always be the same length. I've noticed often that with carbon fiber rods, even industrially wrapped ones, the butt section is a little longer than the rest of the sections - be it two piece, three piece or four piece. I always mount the stripping guide at an arms lenght just as suggested correctly above. I also agree that there is an error with the math somewhere!!!