I don't know if its there and I haven't found it or if its been asked for before but......
It would be handy to have a fill adjustment where you could make the top X layers of infill a higher resolution.
This would be similar to the "dense support" function.
That way if your model could withstand a very low percentage fill, but needed a tight fill on the uppermost layers to support a top face , you could do it
I could print a box with 10% infill up to the top 10 layers or so, then increase the percentage to 40% for a finer finish to the top
It would be quicker and save some filament.