Note to presenters: If you use unqualified terminating phrases like “To summarize,” “Just to finish up,” “In conclusion,” “And for my final slide,” or “I’ll leave you with this,” and/or you put up a slide titled CONCLUSIONS or SUMMARY or both, you had better be pretty close to done with your presentation.

If these occur with 20-30 minutes left in your talk, especially if your talk was only supposed to be 15 minutes to begin with, even worse.