The first example is strict bem, the second one less. Which of the following examples is more bullet-proofed (browser compatible, code readability, reusable etc.) :

<div class="block">
    <h1 class="block__headline">Headline</h1>
</div>

or

<div class="block">
    <div class="block__headline">
        <h1>Headline</h1>
    </div>
</div>