I try to open up a few thieve troves since a couple of days but I have to observe that while for normal treasure chests the ratio of visited location to spawned chest is about 2:1 or even 3:2 it is more like 10:1 for thieves troves.
This indicates that a lot of people are either farming thieves troves like hell (combined to the slow respawn this leads to emptied world - not even zones - world!) or there are bots out there...