Hi Jo,
We have implemented this multiple times for clients.
This is probably the most asked for addition to Totara functionality along with automatically updating user's learning plans with changes made to evidence items (i.e. courses) added to competencies that users already have in their learning plans.
We have done the creation triggered by importing user data and we have also done a version where the learning plans are created and updated overnight or when the user logs in (which ever happens first).
We use the standard competency settings (using mandatory to work out what should be send through to the learning plan) associated with position and organisation hierarchies and the Learning plan settings to work out who will get what.
We have also applied different learning plan templates to different types of users as part of this (ignoring the standard use of only the default learning plan template).
All these required additional development to get working.
David