That is not what I meant. If I understand your question, what I am suggesting is a one-time setup.
You say you have ‘other pages to read posts’ of a specific topic. Lets say that the page template file is called specialtopic.php and you assign a category to the topics you want on that page. Get the category id. Say the id is 10, copy specialtopic.php to category-10.php and you are done for that topic.
Lets say another topic is assigned a category id of 22. Copy the php file that you want to use for that topic (or rename it if no other category uses it) to category-22.php. Done!
Then you can use the Category Widget to direct your viewers to the page that is unique to that category id.
If that is not clear, please post one of the category names that you use, with its id and the name of the php file that you want to display that category.