According to ArcMap help, I'm supposed to be able to open the Measure Layout Tool in the Production Cartography toolbar:
Customize > Toolbars > Production Cartography.
However, my Arc version (10.4) does not have this toolbar. I simply can't find a layout measure tool, which is completely ridiculous. The measure tool that I can find only works for map elements, but not for layout elements such as text boxes, data frames, etc.
If you can't measure layout elements how do you create decently laid out maps?
I'm sure I'm missing some simple step or connection. . . though the difficulty I am facing while looking for this information (google searches, tutorial videos, etc.) plus the unavailability of this tool (or any measure / ruler tool in cartographic toolsets) has driven me to ask for advice.