Quick question / comparison with your experience: If you print very low layerhights e.g. smaller than 0.05mm, do you also need to raise the flowratio very much?
Currently, I print a thing with 0.05mm and my flowratio is 120% compared to 0.2 or 0.1 layerheight…
Extrusion volume regarding layer height should be adjusted automatically by slicer program, you don’t need adjust it manually.
BTW, If all other conditions are equal, lowering layer height means extrusion volume being decreased. It means flow rates would be decreased.
If you have to adjust the flow rate that much, the your extruder is not calibrated very well.