It will understand more than 3 decimal places but only if you type in in manually. It displays a rounded number. Like I can make a line be 1.0065 and be accurate but be displayed as 1.007.
I’m working with ratios between rational and irrational numbers like Pi and Phi and the snap tool won’t exactly match up with points because it’s a few thousands off. I have to max zoom in and add ~0.001 to ~0.003 to get midpoints to actually line up.