Some Gov. agencies require a scale bar on the drawing especially surveying, topo's, site plans and plats, etc..
These are very convenient and you can figure out and use these using a Eng. or Arch. scale, to check against or use.
Remember that it'll scale even if your print is NTS!
I'm sure appropriate scale bar's are downloadable.
In the Field there are a few things you can measure for QA purposes against certain drawings, with a common known size's,
measure against Doorways, or Sidewalks, Structural frame spacing. Main Door residential are usually 3' but could be 32".
Steel roof framing is usually a consistent framing per design. All the Trades have various standards the old staying goes,
"the more you know..." the better. I usually use the ceiling plan for quick referencing, routing and spotting woes...
I wish i never sold my old Hp pen plotter. Probably no access to pens now...