[LeifCarrotson]

No, it's typically ~0.4mm out of tolerance.

Perhaps gear meshing was a bad example requiring higher tolerances. You'd not be able to set the depth to a tolerance of a few microns, but you'd know if you were off by a factor of 2 due to confusion calculating diametral pitch vs OD.

We most recently used it to check timing belt compatibility, whether the belt could be installed over the pulley using the very limited travel available in the belt tensioner, or whether we needed a pulley with smaller flanges or a different way to adjust and change belts. Trying to figure out in CAD whether you could stretch a belt over the pulley, or slip the pulley over the shaft while the belt was pre-installed, is pretty difficult. Printing it and proving that it was easy cost $2 and reduced risk a lot.