O.K. "Safety Sam" is going to chime in here . . . ;-)
When I was hunting, I'd often leave a load in my rifle (uncapped or unprimed of cours) and seal the nipple or touch hole. Actually, over the years, I've worked on a number of antique rifles and it was not uncommon to find them loaded - I've run across a number of them. Several, after unloading and pulling the breech plug, looked pretty good. Others, where moisture hand gotten to the powder over the years, were pretty crudded up. I think one of the biggest problems that might occur in leaving it loaded is if you have it out in the cold and then bring it in to a warm area which will probably promote condensation. If you cover the nipple or touch hole though, you should be fine. I always uncapped and placed a couple of cleaning patches or a lightly greased patch onthe nipple and then lowered the hammer on it. On a flintier, I used a section of round toothpick - just be careful not to break it off in the touchhole.
Yes, you know your rifle is loaded if you leave it that way . . . but when you're done hunting, UNLOAD it. I was on the line one time down at Friendship when a younger kid (probably 20) walked up next to my station and he had his CVA. When the range officer gave the OK to snap caps before the match, this kid capped his rifle, pointed it towards the ground and when he pulled the trigger . . KABLOOM. To me, it sounded like I was standing next to the 10 pound Parrot Rifle I used to fire. Needless to say, I was not happy but not as unhappy as the range officer. The response of the kid? "Ahhhh . . . I guess I forgot to unload it after deer season." I chose to step back and not shoot next to him.
If a pair of '51 Navies were good enough for Billy Hickok, then a single Navy on my right hip is good enough for me . . . besides . . . I'm probably only half as good as he was anyways. Hiram's Rangers Badge #63