Also keep in mind that holes or rods (assuming you mean circular) isn’t even absolutely precise to begin with in the file format being used (STL). How many n’s are in you n-gon? 
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Thanks again for the info. When I watch my print being made, the z axis step size reported by Octoprint is 0.0025mm. Which translates to approx 0.0000984" (I round this to 0.0001). Given my incredibly bad memory, my internal numbers tend to change a lot. A mind is a terrible thing to lose. I fight it by using the notes app on my phone.
The cheat sheet I am talking about will be a compilation of this and things that have worked for me. Since wasting plastic is a relatively cheap hobby All I have to do is keep track of my numbers. Decimal points make my head hurt.
You might also consider collecting data from other CAD tools. My experience with Sketchup was miserable. The software was designed for landscape CAD, measurements in feet. When they tried to adapt it to mechanical drawing, there were many precision issues in the rendering mechanisms. Maybe it has become better in the past 2 years.