Do you need to mark metalness maps as "Alpha from greyscale" on the import settings

We noticed that our textured models just didn't look the same in Unity as they did in Quixel. Too shiny. Someone said what happens if I tick "Alpha from greyscale" on the import settings, I said "surely not", tried it and hey ho, no more shiny character. We've checked the model out to make sure that things that are supposed to be shiny are shiny etc etc. It all looks good to us. So is this what you're supposed to do?