.... most of times i don't bother with the real world sizes of the objects i want to use in my scene.
It's like watching a movie - as a viewer you only get to see, what the director "wants" you to see and "wants" you to make believe ...
A lots of action in front of the camera, but you don't get to see the people standing behind and saying cut or action.

That's the way i set up my scenes most of times. Everything that fits my scene and looks the way i want it to, will be positioned and scaled fitting into the picture. If my landscape is 100 meters by 100 meters in Vue measurements in size and i want it look like 10 times this size, well then i will scale down a poser figure and position it into that landscape, so that it will give the impression to the viewer, that it "is" that size. Depending if atmosphere, haze, fog, clouds work in size with the scene i want, so i keep scaling anything i use up or down until it's looking right ...

Since i can see the real world with my very own eyes, i believe i've got a good natural measure in my sight, to tell what looks right or wrong most of times - so original perfect scales in each object is for me just a slow down in my workflow, trying to get everything in scale with each other.

Anything that matters for me, is the outcome of the image - since i don't do animations, the scale is no factor me at all. In animations realistic scales might help - but with one computer to use, animations are for me a no,no anyway ...