Should element ceilings only be filled and sanded, or covered with fleece?

Streichputz is more or less wall paint with quartz sand; I believe it comes in sizes from 0.5mm to 2mm and possibly more. I don't know what the individual manufacturers call it. I know and like: Haering Streichputz in 1mm; I found the 2mm version harder to apply on the ceiling as a layperson. But it surely also exists from other manufacturers or you can make it yourself if you want, simply with quartz sand. I think Haering calls it Silikat Deko Quarz.