O'Reilly logo
  • Pranav Gupta thinks this is interesting:

You can add segments to a path with the Pencil tool, regardless of which tool was used to draw the path, and whether or not the path has an applied brush stroke. If a path does have a brush stroke, you can also add to it by using the Paintbrush tool.

From

Cover of Illustrator CS6: Visual QuickStart Guide

Note

Ways to add segments to a Path
1. Add anchor points
2. Use Pencil tool
3. Use Paintbrush tool if the path has brushes strokes