If you dont mind using a one stop solution for Task Management System instead of viewing them in Markdown files you can consider trying out CardBoard Plugin, to see all your tasks in Kanban View.
A more powerful plugin is under process of getting released to the Obsidian Plugin Marketplace called Task Board. This will give you much more features to manage your tasks efficiently and sorting tasks based on the date of completion, etc.
You can go through this topic, to see how using a single Board for Task Management can be a better GTD methodology : Task Board : Another GTD methodology | Similar to GitHub Projects Planning