One must be careful about the placement of a scarf joint. On top of a post may actually be a poor choice, as this may be the point of the highest bending moment. One can create a scarf joint that is quite strong in tension, but one that is strong in bending is more elusive. This has been
discussed at length here on this forum . Also, see Jack Sobon's article:
Historic American Timber Joinery part VI Scarf Joints. This is available as a
free download from the Guild's web page.
