How should an ADI decide when a learner is ready to move on to practising a new, more advanced skill?

1. Automatically after a fixed number of lessons, regardless of current performance
2. Based on the learner consistently demonstrating competence and safety in the current skill, not just on the number of lessons taken
3. Whenever the learner asks to try something new, regardless of current ability
4. Only when the learner has memorised the entire Road Code