Ah yes! The answer to age old dilemmas.
Years ago when I misspent my youth working on cars, I could tell the size of a bolt/nut by glancing at it. Even metric due to the typical cad or bright nickle plating and head stamp.
Now the only thing I remember is righty tighty which works in a few cases.
The labeling is ideal, but remembering where I left my only working marker puts that plan on hold.