How does a PackedScene work when passed in an exported variable

To my beginner understanding, in order to use a scene saved on the drive, one must first use ResourceLoader.load() to load the scene to acquire a PackedScene, then instantiate it using PackedScene.instance() to acquire the Node that can be finally added as a child.

Following this principle, one can easily export a script String variable and use it to set which scene will be loaded by a node – even with convenient hints like this:

export(String, FILE, "*.tscn") var scene_path 

But that’s not fully descriptive in my opinion. I want to select a scene – an only scene – in that exported variable. Looking around the internet, this Godot Q&A post mentions one can export a PackedScene variable like any other to link to another scene. So I immediately thought of this:

export(PackedScene) var new_scene = null 

This looks much cleaner – especially the ability to initialize it to null, as well as having access to methods like can_instance() to catch any accidental false inputs int the editor… however, this looks like there is one important link of the chain I mentioned at the start missing. In the end, I’m still selecting the PackedScene as a path on disk, so when does the load() happen?

Is this a valid and correct use of the export keyword, or could this come back to haunt me later if I overuse it?