Optimizing Django / Wagtail Queries for a Blog

Question

I'm using Django and Wagtail 5.x to build a blog. At this point, I'm trying to increase my understanding of query optimization and decrease the number of necessary db queries by implementing select_related. To my knowledge, I can use select_related to essentially chain related queries. In other words, when I'm accessing the db for the categories associated with CarHubPage, I can also get the posts related to those categories simultaneously. I assume it caches the results, so when I actually access the category's posts in the template, it will not require another db lookup. Is my understanding correct?

However, testing with and without select_related produces the same results (testing with Django toolbar). So I need help making sense of the inner workings and whether my approach/understanding is correct.

What's the best approach here?

class CarHubPage(Page):
    intro = RichTextField()
    youtube_embeds = StreamField(
        [
            (
                "Youtube",
                YoutubeEmbedBlock(),
            )
        ],
        use_json_field=True,
        null=True,
    )

    content_panels = Page.content_panels + [
        FieldPanel("intro"),
        FieldPanel("youtube_embeds"),
    ]

    parent_page_types = ["BlogIndexPage"]
    subpage_types = ["CategoryPage"]

    def get_context(self, request, *args, **kwargs):
        context = super().get_context(request)
        context["posts_per_category"] = (
            self.get_children().live().specific().select_related("category_posts")
        )

        return context


class CategoryPage(Page):
    intro = RichTextField()

    parent_page_types = ["BlogIndexPage", "CarHubPage"]
    subpage_types = ["BlogPage"]

    content_panels = Page.content_panels + [
        FieldPanel("intro"),
    ]

    def get_context(self, request, *args, **kwargs):
        context = super().get_context(request)
        return context


class BlogPage(Page):
    category = ParentalKey(
        CategoryPage,
        on_delete=models.CASCADE,
        related_name="category_posts",
        blank=True,
    )
    author = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.PROTECT,
    )
    date = models.DateField(default=date.today)
    snippet = models.CharField(
        max_length=200,
        help_text="Excerpt used in the article's preview card.",
    )
    featured_image = models.ForeignKey(
        "wagtailimages.Image",
        on_delete=models.CASCADE,
    )
    tags = ClusterTaggableManager(through="BlogPageTag", blank=True)
    body = RichTextField()

    content_panels = Page.content_panels + [
        MultiFieldPanel(
            [
                FieldPanel("author"),
                FieldPanel("date"),
                FieldPanel("tags"),
            ],
            heading="Blog Information",
        ),
        FieldPanel("snippet"),
        FieldPanel("featured_image"),
        FieldPanel("body"),
    ]

    parent_page_types = ["CategoryPage"]
    subpage_types = []

    def save(self, clean=True, user=None, log_action=False, **kwargs):
        self.category = self.get_parent()
        return super().save(clean, user, log_action, **kwargs)

Specifically focusing on:

    def get_context(self, request, *args, **kwargs):
        context = super().get_context(request)
        context["posts_per_category"] = (
            self.get_children().live().specific().select_related("category_posts")
        )

        return context

Template (just for testing purposes at the moment):

    {% for cat in posts_per_category %}
    <div class="row">
        <div class="col-lg-6">
            <h2 class="mt-4">{{ cat.title }}</h2>
        </div>
    </div>
    <div class="row">
        {% for post in cat.category_posts.all %}
            {{ post.specific.snippet }}
            {{ post.specific.title }}
        {% endfor %}
    </div>
    {% endfor %}

I've also tried, self.get_children().live().specific().select_related("child") - but I believe select_related only works with a ForeignKey relationship?

Thank you. Any other advice is also appreciated.