Insert static meshes in blueprint vs directly in world outliner

I am pretty new to Unreal Engine and I’m still to get the workflow.
I’m trying to build a complex house composed of many props and I’m not completely sure how to proceed.
I thought a good way to go was to create a “Master” blueprint containing the entire floor of the house in which I’ll place the walls, floor and ceilings. Then I will place other blueprints inside the master blueprint like windows and doors, then the props. Finally I’ll place the master blueprint inside the World outliner so I can move everything like one group.

But then, when I watched some speedlevels, I noticed that every object was placed directly inside the wqorld outliner.

So, what is the best way to proceed? There are performance differences between the two ways?