When I was a young lad, I had an uncle who was a Mountie. He had a few guns: a .22 target pistol, a Mossberg .22 magnum, and his service revolver (model 10 S&W Military and Police) If I would ask him, he would show them to me and he told me right off: "When you pick up a firearm, ALWAYS check to see if it is loaded" and he showed me how. I have remembered that to this day, and every time I pick up one of my guns, I immediately check it for a loaded chamber, even if I have already checked it, and handed it to someone. I also encourage someone to do the same, even though they have seen me check it. How can it be too much trouble? Handling firearms is a great joy.
I leave my hunting rifle loaded, providing I have not fired a shot out of it. I open the frizzen, and put a layer of duct tape on the frizzen face. That reminds me that the rifle still has a load, and prevents anyone else who might drop the hammer, from an accidental discharge. If the weather has been misty, damp, or in any way wet, I discharge the rifle at camp, clean it and re-load it for overnight storage. As BITW says, not much use without a load in it.
I did a test a couple years back using Lehigh Valley Lube on the patch in a clean section of barrel. I left the black powder loaded barrel stub outside on my fence, but under cover for several days and then checked it. It was typical fall weather and without rain. The perfect bore had been oxidized by WATER in the LUBE. Whether it came from the atmosphere or from the lubricant, I don't know. But I know one cannot use LVL for a hunting lube and leave it for any length of time without rust in your bore.