What sets monday.com apart from other collaboration tools is that you can add multiple owners to a task at an item level. However, this could sometimes lead to confusion if you meant to directly assign a specific component of the task to a group member.
In the scenario mentioned, using the sub-item feature can be very useful. You get to breakdown the parent task to its components and track the completion of each while still getting the whole picture.
To help you in maximizing the potential of sub-items, I have put together some recommendations on when to use the monday.com sub-items.