I am working on a undeground fps map for our project Independent Zone, since developer decided to change from exterior to interior.
First stage was whiteboxing a level inside unity with a couple of prefabs representing doors, walls with a scale of 1 unit in unity = 1m
I mean really few, one door and one straight 1m long wall.

Right after i created a first part a small hall with elevators with real life scale in mind, i came to conclusion that i it will be better to use larger scale of assets. Sense of scale from a player POV and real life is really different.
For example: I thought it would be ok to have tight corridor like 1m wide. When i tried to play it, it was not tight, it was super tight. Based on this knowing a decided to double the scale considering 2m wide corridor as tight 🙂
Right after the level was approved by the developer i started to plan assets modularity in blender.
This is the first modularity idea. Colors represents different assets.

@smurfmier1985 Miranda, i think this might be helpful to you 🙂