If the mechanics are the same as previous games you can leave things lying about but you cannot store them in containers.
The mechanics are a little different in this one. I'm still testing it to figure out exactly how, but so far I've found that residences are very random. Some respawn, some dont. Some have partially respawning containers.
Spouse properties I believe have respawning containers, which stop spawning after marriage. Could be the same with a friends property, but it needs more testing.
Dungeons are different, and almost always respawn.
Basic rule of thumb, dungeons take 30 days to respawn, other cells take 10 days.