Discovering that PrusaSlicer settings for Prusa's own filaments are not always accurate
I have a project I'm working on where I'm using Prusament PC Blend and the parts have to be dimensionally accurate. Polycarbonate shrinks (and warps) when it cools so it needs to be compensated in XY and Z (somewhat). Prusa sets the shrinkage compensation to 0.18% for PC Blend but with the rolls I have, I'm measuring 0.71%. That doesn't seem like a large difference but on long 300mm spars which I need to print, the difference equates to ~2mm.
The question though, is how accurate do you need this and does it even matter? If you are printing Gridfinity boxes or fidget toys etc, then the answer is "no". The default settings are more than good enough. If you are printing functional parts that need to be super accurate (alignment of screw holes for example) then it is a good idea to calibrate the filament even if a vendor provided profile is available.