Level streaming, to what degree?

I am working on a platform game, where in essense I want to keep each area as closed of and contained as possible.
For that I am considering making each new area a new level, in theory every time you go trough a door into the depth of the screen you will enter a new level.

Since i don’t want that level to load when you go trough the door, we got level streaming. But to what degree should I use it.
Either I have a small area around each passage, that will start loading the area it will lead to.
OR I will load all levels that you might each from the one you are in, the decision between those two comes down to, how fast is unreal when it comes to stream or load a new map.

In theory the passage could just lead to a one screen empty room, or to a multiscreensized room with a boss and multiple enemies and items.

What are peopels suggestions? Does this belong in Blueprints or content creation??? :S

The solution depends on your sections, more textures will take longer loading time as geometry remains memory light. From standard use, i find loading times pretty fast actually to load small maps.Perhaps you could give a try at loading sections. About streaming as in the example demo, it unloads previous levels sections and load new ones as you move near a new section, this can be needed if your camera can see next or previous section from your actual position.

I think platform also plays a big role. If you are on mobile, you may need smaller stream sizes, whereas on PC you could get away with larger streams.

What else is going on in your game at any given time is also important. Really hard to say without testing.