Why am I unable to display my custom attribute?

I am adding attribute example. I don’t add to any group, so it’s not present in Deafualt attribute set.

                'type' => 'example',
                'input' => 'textarea',
                'frontend_class' => 'no-whitespace validate-no-html-tags',
                'label' => 'example',

            'group' => '',
            'sort_order' => '',

            'backend' => '',
            'frontend' => '',
            'source' => '',

            'default' => '',

            'wysiwyg_enabled' => false,
            'is_html_allowed_on_front' => false,

            'used_for_sort_by' => false,

            'global' => ScopedAttributeInterface::SCOPE_GLOBAL,
            'visible' => true,
            'required' => false,
            'user_defined' => true,

            'searchable' => true,
            'visible_in_advanced_search' => true,
            'search_weight' => 5,
            'filterable' => false,
            'filterable_in_search' => false,
            'comparable' => false,
            'visible_on_front' => false,
            'used_in_product_listing' => true,
            'unique' => false,
            'apply_to' => '',
            'used_for_promo_rules' => true,

            'is_used_in_grid' => false,
            'is_visible_in_grid' => false,
            'is_filterable_in_grid' => false,

            'is_required_in_admin_store' => '',

            'system' => 0

Next I add set Test:

$this->attributeSetFactory->create() ->setEntityTypeId($this->_entityTypeId) ->setAttributeSetName('Test') ->setSortOrder(50) ->initFromSkeleton($this->_defaultAttributeSetId) ->save();

Next I add example to Test:

$attributeSetId = $eavSetup->getAttributeSetId($this->_entityTypeId, 'Test');
        $groupId = $eavSetup->getAttributeGroupId($this->_entityTypeId, $attributeSetId, 'product details');
        $attributeId = $eavSetup->getAttributeId($this->_entityTypeId, 'example');

        $eavSetup->addAttributeToSet($this->_entityTypeId, $attributeSetId, $groupId, $attributeId, 50);

Effect is:

example is not in default - so it’s ok.

example is inTest - that’s what I want to achieve!

But if I enter new/edit product - I can’t see my attribute, neither in Default nor in Test:

They would be visible if I add attribute also to Default (have already tested that), but then it doesn’t make sense to use Attribute Sets at all.

Am I correct - if I have my example in Test, when I enter new/edit Product page and change attribute set (then page reloads dynamically) also example should be visible?

Of course after adding attribute to set I tried many times reindexing, cache cleaning and so on. Does anyone has a clue, where I should look or what I should check?