The wax does gum up, and does keep it in place somewhat, but the wax doesn't last forever, and it likely won't be around by the time something breaks.

When I do single lashing, I tie off the end of the lashing with a seized slip knot and pull the free end of the line through it, then pull it tight (I've heard people call this an "eskimo knot"). Then I use a big sailmaker's needle to thread it through the holes, but I don't pull it 100% tight, just snug. To tie it off, I use a knot around all of the strands in the same way that you would do the lashings holding the stem pieces to the gunwales. The knots tighten it, I'm not really pulling on anything. At least not in the same way you would with continuous lashing.

That said- Morris does the best of any of the other texts when it comes to discussing lashings.

m