There seems to be a fundamental difference between lectures in academic and pedagogic settings. In the former (e.g., in academic conferences) you seldom repeat the same lectures, at least not in the same language, while in the latter repetion is the rule. There are pros and cons in reteaching the same courses every year or at any other interval.
Full-time faculty members at Israeli universities are required to teach four courses a week. My ideal is to "scrap and (re)build" each year each course I am supposed to reteach. But it goes without saying that this ideal is not so realistic. In order to scrap and (re)build all the four courses every year I have to spend an enormous ammount of time. You can find such free time either if you sleep less than three hours a day or if you have at least 30 hours a day.
The biggest advantage of reteaching the same courses is that you can reuse the same written materials which are already prepared. But this is the most problematic part in "recycling" courses. On the one hand, you are familiar with the materials you are supposed to (re)teach. But on the other, you become too familiar with them (and are liable to lose intellectual enthusiasm about them). This is the worst con of this padagogic "recycling".