I agree that the guns dont instantly turn to junk if not cleaned right away. I used to have a cheap 44 Navy copy that I left loaded all the time, it lived in my truck. I'd shoot it once a year, or whenever I thought about it. One time I figured I'd shoot it, since it had been a year since I messed with it. I dug it out, and saw that it had been shot,...and not cleaned, for a year. I was a bit concerned, but it cleaned up fine, if possibly some tiny pits in the bore. Nothing to have a cow about. It was northern Az.
I bought an Uberti Navy. It was dirty, and I had no idea how long it had been left dirty. I bought it cheap. It cleaned up pretty well. It had some minor pitting, but shoots quite well. I'm rather happy with it, and give it no thought regarding the condition of the barrel. If I needed a gun to be ready, I'd probably load it as is, and deal with cleaning it when it was convenient. If I had time, a couple simple damp patches down each chamber and the bore, then dried out with patches, then loaded would probably be fine for as long as one chose to leave it that way.
I used to keep the Navy and an Army loaded all the time. I left them both loaded a year or so a couple times anyway, and they shot fine. The Navy had one slight hang fire I believe, but it fired, and I couldn't tell any loss of power. It killed bunnies just fine. One of the members here bought a couple Civil War period guns that had been found under the floor of a barn, most likely put there during the war. They had been wrapped in oily rags, but had no other care in the 120-130 years thay had laid there. One had been rusted on one side, the other looked ok. He used fresh caps, and both fired. The Navy, which had the rusty side, had a few hangfires, but it did fire.
I currently have a Colts Dragoon that I loaded when I bought it about 4 years ago. I haven't fired it yet. Will report when I do, I've been wanting to shoot it. I dont expect any troubles.
I believe the popping caps on nipples to be a modern idea, done after storing a gun that has been left oiled. I generally load mine right after cleaning them, and don't oil them (chambers) and don't pop caps before loading them when loading dry. I've never had a problem doing it that way, with rust, or with them firing.
I beleive open top holsters were fairly common. Reading in the book "Packing Iron", open top holsters were common after the war, even before in some palces, spreading quickly. I think caps are more damp resistant then most of us believe, and the old caps were probably better yet.