What is the least effective use of presentation aids you’ve witnessed? Based on this chapter, what advice would you give to that speaker to How can you determine when you have rehearsed long enough...

What is the least effective use of presentation aids you’ve witnessed? Based on this chapter, what advice would you give to that speaker to

How can you determine when you have rehearsed long enough that you can extemporaneously deliver your key ideas to your listeners, but not so long that you are giving a memorized speech?