In the past, when I was using irr map with low subdivisions and the “medium” preset, I’d get splotches where surfaces are too close together. It made sense.
Now, and this is really good, I don’t get splotches even when I use, say, 40/20 and the Medium preset.
I remember people recommending using 70 to 100 subdivs in interior scenes, about 10 years ago.
Whatever it is (lighting or retrace in LC) those numbers are way too high now.