The education authority where I teach navigation classes in the evening have recently been tightening up their paperwork in an effort to improve the standards of teaching.
One of the results has been that tutors have to be able to show written lesson plans for each of their sessions if their class is inspected.
Although I always have a written plan at the start of the courses it is by its nature fairly broad. As the courses last for 20 weeks and you have no idea or the level of experience and formal education of the students before the course starts, it is hard to predict exactly what will be taught on any one week.
I have been creating a lesson plan for each individual lesson that relates more closely to where we are in that course but to borrow from the old military saying: "The plan rarely survives contact with the students."