If you want a perfect 3D view and you don't care about the size of the file, you have to make it like in real life: combined piece by piece.
You will see you will have to accept some compromises.

Yes. absolutely !
It looks like you made the entire roof and exported as an object file by the name Roof and imported it in my project file. The groups beneath the imported object is something I need to figure out. I will have to spend some time on it to understand the logic on how you made it. Thank you very much for sharing.

The perfection exist only you make it.
SH3D is good to show to constructors what you want in final, not to teach them how to do.
For colors and nuances I recommend to listen your wife.
It's good for your health.

Strongly agree !