In the Didaktikos issue for November 2019, Sean McGever has an excellent essay on lecture preparation (24, 26–27).
Using a baking metaphor, McGever encourages chronic over-preparers not to “overwork the batter” of their lectures so that they don’t come out overly dense.
McGever gives several practical suggestions about how to avoid overworking a lecture.
These begin with and derive from careful thought about the learning outcomes for a particular course and a particular lecture within that course and include thoughts about how efficiently structure notes and slide decks.
For all of McGever’s thoughts, see his full essay in Didaktikos.