besides the sheet draftscale value there exists a couple of macros for automize this task.
One originally came from Klaus (www.incobase.de) which I modfied a little to fullfill my concept of drawing scale.
It calculates all scales on a draeing sheet (only principal views) finding the master scale and all second scales.
This will be written into a draft property (or 2) for use in the title block.
"I can overlay two printouts to get a visual idea of interference"
It's been so long since I used that technique that it didn't really register. Seems to me you need very translucent paper like old vellum paper or mylar and/or a good large light table. Neither one in supply where I've worked in years. And if the scale is fractional because the parts/assemblies are large the resolution is going to be lousy.
Although I thought the argument for scale you made supported indicating scale in some cases at least and perhaps having that argument in mind is why gov't standards still require it. But then I'm imparting the virtues of logic and reason to gov't regs and therefore may be, umm, out of my mind.
I'm not sure I follow that as most CNC apps that I am familiar with that do anything besides 2D sheet metal take 3D formats like STEP/IGES/Parasolid, and of course sheet metal flat patterns can be exported directly to DXF for those CNC situations...