Can someone plz tell me that are subjects like OOAD(object oriented analysis and design) or requirements engineering actually useful in real projects and jobs...?

They will end up being very useful in non-obvious ways in my experience.

Never thought much about design patterns and best OOAD practices until I got to work on an Enterprise application. They are really useful and I recommend not blowing off the classes that cover these concepts; even if they are torture.

Depends... basically the idea of how to break up large problems into smaller independent parts, helps a lot... otherwise you get God classes and spaghetti code

... and debugging will drive u crazy.... (guess who has to fix production issues but the code looks like crap?)