I have found that in a large module or semi-persistent world that is not DM managed, you need re-spawning everything. This goes for bosses, and plot items, keys, etc. After getting all of this in place, I found that some of the visitors seemed to want to take advantage of re-spawning chests...hmmm...and get a lot of loot for little work. I had a heck of a time getting DelayAction to work, and after a few hours of trying several different methods (like ActionWait, etc) I found a nearly working script in the archive for delaying the creation of an object.