I have always considered fractional measurements to be for the building and furniture trades. I have worked in the machinist trade for 30yrs and have always used decimal measurements in thousandths of an inch and mm. Some tolerances greater than 0.030"+or-, will be called out in 1/32ths". I have a Starrett 8" vernier that will read to .0001" but seldom use it as I have access to micrometers that are quicker to use. Another seldom used scale for large diameters is a pi tape.