The answer to your question is as simple as it is unsatisfying. Additional degrees of precision in construction are only as useful as your means to use them.
If you using your saw can only cut to an accuracy of 1/8 of an inch, than any precision beyond that point is lost as you are unable to actualize it
However if you are using a saw and you're now at the point of your personal skill that you're measuring to the inside or outside of the mark on a ruler, then it is likely time for you to graduate between more precise form of measurement.
https://youtu.be/qE7dYhpI_bI?si=HCtTbklCA18ZieCh
This video covers a lot of the interesting points around measurement and how we can never truly be perfectly accurate with any measurement of any non-discreet metric.
To give a real world example if you are off by a millimeter diameter when building a car engine cylinder it will likely fail.
Boy do I have bad news for you about every other word that exists in every single language. There is no word tree we harvest fresh ripe new words from, everything is made up. We are just meat squirting air through our various holes because we like the sounds they make and wish to communicate thought.