OK, springs wear out from repeated cycling, not from constant compression. That being said, I keep my doubles (all used for HD) with chambers empty and the hammers down. I rubber band 2 shells to the barrels just ahead of the forearm so I am ready to break and load the gun RFN. Each has a butt cuff with 6 extra rounds in it. I cannot imagine a HD scenario that will require more firepower to prevent an entry, or to terminate one already made. 2 of my coach guns are Stoegers, a SXS and an O/U, 2 others are a repro hammer gun, and a Stevens 311R. All are stashed concealed near likely points of entry.
If you want to keep yours loaded and on safe it will not hurt the gun. I keep mine the way I do because I keep all long guns "cruiser ready", that is mag loaded, chamber empty and I want to keep everything uniform so I know that I have to chamber a round in ALL my weapons. Never have to think about it that way.