Magento2 Overriding Block and Model Working Only For Direct Called Class

Question

It seems like Overriding Block and Model in magento2 work only if the class is directly being called.

For Example i want to override model file

vendor/magento/module-catalog/Model/Layer/Filter/AbstractFilter.php

Here is my di.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">    
    <preference for="Magento\Catalog\Model\Layer\Filter\AbstractFilter" type="Mynamespace\Comman\Model\Layer\Filter\AbstractFilter" />
</config>

And This is my AbstractFilter.php

namespace Mynamespace\Comman\Model\Layer\Filter;

abstract class AbstractFilter extends \Magento\Catalog\Model\Layer\Filter\AbstractFilter
{      
    public function __construct(
        \Magento\Catalog\Model\Layer\Filter\ItemFactory $filterItemFactory,
        \Magento\Store\Model\StoreManagerInterface $storeManager,
        \Magento\Catalog\Model\Layer $layer,
        \Magento\Catalog\Model\Layer\Filter\Item\DataBuilder $itemDataBuilder,
        array $data = []
    ) {

        parent::__construct($filterItemFactory,$storeManager,$layer,$itemDataBuilder,$data);
        if ($this->hasAttributeModel()) {
            $this->_requestVar = $this->getAttributeModel()->getAttributeCode();
        }
    }

    /* i want to override this function*/
    protected function isOptionReducesResults($optionCount, $totalSize)
    {
        return $optionCount <= $totalSize;
    }
}

This is not working because AbstractFilter is not being called directly from anywhere.

If i do same thing for

vendor/magento/module-catalog/Model/Layer/Filter/Price.php

It is working fine.

I am facing same issue for class:

vendor/magento/module-bundle/Block/Catalog/Product/View/Type/Bundle/Option.php

Which is not working however classes

vendor/magento/module-bundle/Block/Catalog/Product/View/Type/Bundle/Option/Checkbox.php

vendor/magento/module-bundle/Block/Catalog/Product/View/Type/Bundle/Option/Radio.php

which are working fine.

Can someone guide me if i am wrong here.