Setting installed height

What tolerance do you guys use for setting up the installed height? Comp and Lunati both say +- .020 is acceptable but I’ve got shims down to .005 so why not get them closer? I’m currently setting the installed height on my brand X speedmaster big block heads and they were all over the place as assembled from speedmaster. Glad I checked. Right now my spread is 1.890-1.906. Shooting for 1.900. Thoughts?