Why should an ADI set a clear objective at the start of each lesson during the briefing stage?

1. Objectives are only a formality with no real effect on the lesson
2. Objectives are set only for the learner's final test lesson, not routine lessons
3. Setting an objective replaces the need for any practical driving that day
4. A clear objective focuses both instructor and learner on what specifically is to be achieved, guiding practice and the later debrief