I've found that a structure that gives obvious "book-ends" around each topic make it easier for the audience to follow.
Most of my talks lately have been either 4-5 small case studies or a Top 10 List. Each case study is a repetition of "who are the players, what happened, what did we learn". The repetition gives the audience a clear understanding of "we're moving to the next topic now" because they see the pattern. In a Top 10 list there is the obvious "book end" of announcing the next number.
I started doing this after seeing too many presentations where the presenter runs topic to topic smeared together with very little separation. Sometimes I get confused because I'm still on the last topic and they've moved on without letting the audience know.
Announcing the number of case studies ahead of time is also useful. You want the audience to be focused on not what you are saying, not subconsciously trying to reverse-engineer the structure you are using.
This is true for writing a paper as well as giving a talk.