Not a scene as such - just, for example, a heavy, multiple item mesh of CAD-type data (e.g. vehicles) that isn't easily made into one mesh plus material selections.
I'm using xrefs but they make the scene so slow to save and open - Corona proxies would be ideal. I tried having the main vehicle in the scene and then having instances of it in the scene (I need different positions for different backplate renders) - but my materials didn't work on the instances - most notibly the decal objects I have set up.
Cheers