Do IT (or hard) silver solders overheat sterling?

I like to use the hardest grades of solder possible, generally hard solder or IT solder. However I have been told the main culprit of Fire stain is overheating your sterling articles. I now use prips flux on my sterling pieces to minimize firestain however I don’t want this to be for nothing by my use of IT and hard solder. Do high temperature solders destroy such benefits achieved by these fluxes?