@Grahame-Lancaster There's no need normally. From my somewhat limited experience, the main reasons to add waypoints are:
- to minimise any dynamic* re-routing - which can happen due to traffic or closed roads.
- To keep HERE and TomTom routes matching, if you;re sharing routes with TomTom users
However, someone else may be able to give better reasons to add them.
*as in on the day whilst you're riding