About the cleaning up phase: the author cleaned up the bitmaps before the vectorizing stage, and that included separating lines.
In my experience it's a little bit easier to clean the vectorized results by removing unwanted points, because those are easier to see than line connections that may or may not pose a problem later. (But to each their own.)
Actually that's my usual approach, but you should see the vector output from these. I tried doing it and than went back to cleaning up the raster images.
About the cleaning up phase: the author cleaned up the bitmaps before the vectorizing stage, and that included separating lines.
In my experience it's a little bit easier to clean the vectorized results by removing unwanted points, because those are easier to see than line connections that may or may not pose a problem later. (But to each their own.)