As Old Crow said, loot respawned in POI just like it does anywhere in the world as long as no player has been near it within the respawn time period. You can rerun a POI a week later (less, but I don't know the exact time) and loot everything again. In fact, if you left something in a container the first time around, when you go back, you can loot that and then wait a second and the container will update to the respawned loot, saying it had not yet been checked and you'll be able to loot it again. It is like leaving paper in a mailbox... when you go back a week later, it'll still have that paper in it. If you loot the paper and wait a second, it will change back to unlooted tooltip and when you loot it again, you'll get a new set of loot. Leaving something in the container doesn't make it so you can loot it again but it hides that it can be looted again because it still shows the old loot. That may be why you think it doesn't change, if you are leaving some loot that you don't want in containers. So, yes, it's a change.