Lesson plans are an effective tool in the hands of a teacher. If for some reason, a day is disrupted, you can simply refine or combine two lesson plans to cover the following day. A lesson plan must not restrict the flow of learning and teaching. If you have planned to cover a certain amount of work and fail to do so, there will always be an opportunity to move onto the concept in a follow-up lesson. Home school teachers who have difficulty being flexible, would be well advised to plan their work in lesson units and not individual lesson units.
Once you have a broad outline for the year, you would add sub-skills which should be covered each semester. You could in the language arts divide the various punctuation marks and their rules up over four semesters. Your language sub skills such as sentence types would have to be covered with the introduction of a statement requiring a period; a question which must take a question mark and so on. You could progressively add to your planning so that by the last semester you will move to the rules for direct and indirect speech, once all the necessary punctuation marks have been covered.
Obviously, an effective teacher will plan for a whole phase or at least year to begin with. The best way to start the four step process to drawing up a lesson plan; would be to begin with a broad overview of the skills, knowledge and desired outcomes for each quarter of the academic year. One can simply plan to make a one page annual summary per subject to be taught. If you are planning for the years work in Language arts classes, for example, you could in your annual draft, plan to start the year with poetry, move onto the novel genre in the second semester, the drama genre in the third semester, and so on.