Thanks for specifying the question, Fauntail!
I read again your initial question, and yes, to my ears it has both in it, holistically as well as numerically.
Since the word set design came in, my mind was wandering in the themes of very small and very large scales. Perhaps more between like a small kitchen set, or a factory/warehouse scale, or even a mile long spaceship (ID4). Which brought me to talk about the requirements from a set designer/art-director, who turns scripts, storyboards, even animatics into something one can touch. Since you told me that you have already intermediate experience with a previous app, my decision to go into that direction was more plausible, than in the other. I missed the target, sorry for your extra time. Just another case where a scene file would have saved time
Here is a little clip, showcasing a typical set up for size, based on your file.:
https://www.amazon.com/clouddrive/share/8nmpsSNoM6xU3y9F7xHpE5KIFa7pGI8PrhcPhS304MD
At 30 seconds, and that is very important, the points move over existing points! So, it can create polygons placed in the same position, or with Normals facing in the opposite direction. This can cause trouble!
Typically, the project size matters, in terms of several aspects, as in IES lights, dynamics, and other parts that might show up wrongly, if we use the numbers just as units. But to build a model, I would go with something like the old rule, to keep the numbers before and after the period equally (It’s an old rule and we have more precision these days, but it can’t hurt.) Pure polygon models can be scaled later on, but always make tests first, before investing lots of time.
During my time working with CAD, I learned to love guides, as well as raster and snapping. Of course it depends on the things one needs to create. To layout ideas with the tools in C4D is certainly a good idea, or just scribble with a spline, perhaps even use the Tools> Doodle to sketch things and see how it works. Perhaps block out the idea with cubes and other standard geometry objects (Primitives) render it and use it as background even, to have less “clutter” in the scene, but you asked without something like that in the background.
Again, since the numbers are so prominent in the interface, I really didn’t got the question of “scale” that way.
Let me know if that answered your question.
Cheers
Suggestions:
https://www.cineversity.com/vidplaytut/photo-realistic_chairs_part_04
https://www.cineversity.com/vidplaytut/guide_lines_and_planes