I despise this structure and the kind of writing and presentations it tends to produce. The absolute worst, which I see all too often in presentations, is its fractal form:

    1. Tell them that you are going to:
        1. Tell them what you are going to tell them.
        2. Tell them.
        3. Tell you what you told them.
    1. Tell them what you are going to tell them.
    2. Tell them that now you will tell them what you will tell them.
    3. Tell them.
    4. Tell them that you are done telling them what you will tell them.
    5. Tell them that you will tell them what you told them.
    6. Tell them what you told them.
    7. Tell them that you are done telling them what you told them.

A structure I like much better which permits the above structure but allows other variations is:

1. Explain how to tell if this is worth their time.

2. Tell them.

3. If there was a lot, suggest what's worth remembering.

The focus here is on how it benefits the audience and not on some arbitrary structural form.