Metroid engine : separated layouts or one big layout?

Hello everyone, at the moment I'm interested in developing a Metroid engine for the sake of learning, but there's still a detail I'm not too sure about, it is about the rooms;

I hesitate between two methods :

One big layout for a single zone, and the room transitions are made inside that layout, or a layout for each room,

I'm not sure which one would fit Construct structure the best, any advices?

Thanks in advance ~

(just to be sure, I'm not asking on how to do room transitions, but just how to compose the world map)

So taking Metroid zones as example, a layout for Crateria, a layout for Norfair, etc, that's the idea?