Builders usually do well to measure .25 inch reasonably, and .125 (1/8)" is not too difficult. but anything smaller, and the comment is, "I am not building a piano here!" or else, "The inspector will never see it!".
I do Autocad plans for landscape installation, including the construction of patio covers, retaining walls and a lot more. Autocad can be accurate to so many decimal places it has become a joke at the office. I have set it to be accurate to 1" for most things, and 1/4" for the most sensitive things. I almost never use the 1/4" sensitive setting.