Nancys diagram curves the line between points and also has large dots at the points, so the path can be slightly confused. In fact, the 12th Planet tends not to make all those pretty curves. Also, there are variations here and there that would make the Path chart too complicated, so that a steady progress or rate of travel does not always occur.
You can assume, in selecting a Right Ascension (RA) and Declination (Dec) point, that no more than .2 RA degrees nor .45 declination degrees occurs at any time as a variance from this path. This variance includes a slower rate along the path than would be assumed and a path other than a smoothed or curved path between points.