Not understanding tolerances is a nuisance in general. We've been happily following a torque driver calibration process that was written up and defined by an electrical engineer...specializing in software and PCB design...

Queue when I had to look up information on replacing the torque tool that has been used for 10 years, I discover its technical range is 0.15-100Nm, ±0.5% full scale. Meaning that if you're using this tool at the bottom of its technical range, your margin of error is 0.15±0.5Nm. Basically worthless. Sure does explain a lot about people on the line complaining that some torque tools suck and would never drive all the way down while others worked fine and some were clearly overtuned despite them all being "calibrated". Oops.

I'll give you 3 guesses where most of the torque calibrations were happening...

They just put +/-.001 on everything they think is important.

My favorite is people putting arbitrary tolerance values that are bigger than the target size of the object. Most of the time, the vendors will figure out the intentions but it's like... God help you if you have to go back to and challenge the vendor when you receive parts in manufacturing that are way out of tolerance and unusable.

Makes you look like a jackass if you look at the tolerances and realize your own genius designer specified a 0.020" thickness but gave it a tolerance of ±0.1". Can't really tell the vendor their supplied parts are trash when your own specs were trash.