Don't have to use excerpt block

source/blog.html

@@ -18,6 +18,8 @@ use:
 
             {% if post.blocks.excerpt %}
                 {{ post.blocks.excerpt|raw }}
+            {% else %}
+                {{ post.blocks.content|raw|split(' ')|slice(0,50)|join(' ')|raw }} …
             {% endif %}
             <a href="{{ post.url }}">Read more &rarr;</a>
         </article>