On what circumstances we should use Object-Oriented

Here's my take on the matter: If there is some piece of data that you are constantly passing around between different subroutines, then that data should be turned into an object, and the subroutines you're passing it to should be its methods. This really shines as the data you're passing around gets more and more complex. If you are maintaining two lists in parallel, for instance. Hiding all that behind an object interface is a much nicer option than manually handling all the data structures.