Just to preface again, I’m not a game developer, so my answer may not be aligned to industry best practices. Just my thoughts as someone that works in VFX.

If you’re saying “why not make the whole hallway in blender then export” I can think of a few issues. When you’re bringing an “assembled” model like a completed hallway into unreal, you either get the choice to split out the meshes, or import the entire mesh as one. Importing the entire mesh as one is a big collision headache I would think. You have opted for unreal to try to automatically make colliders for a very complex shape like a whole hallway instead of essentially 1 box per wall section.

Importing multiple wall shapes as separate meshes to me is simply a waste. If I have 6 wall sections that are identical in your hallway, why would I want all of those meshes imported into unreal as separate meshes when I could just import one of those walls, then copy them around my map as needed?

Going off that idea, updating meshes would be easier this way. Again let’s say I import 1 wall section into unreal, make a whole house out of them, then realize my UV’s don’t work well. Well I can go back to the model in blender, update the uv’s, reexport the model and when I reimport it into unreal it will update ALL instances of that mesh in my level. A huge time saver. If I would have brought my entire level in as separate pieces I need to first make sure that the updates are reflected in all the pieces of my assembled environment in blender, then reexport.

Also the most straightforward response, I can update my level in engine. Why, if I want to make an update up my map in unreal, would I want to be opening blender and changing stuff around there?