Boss mobs in static dungeons spawn too slow

The boss mobs in the Longest Road dungeon, at least TIM, spawns way too infrequently, apparently every 4 hours or so.

This means that even if you do get a team together (or if you solo it at high level), and make it all the way to the end of the dungeon, the chance of TIM actually being alive will be about 1 in 10. (especially true since people log out in the room with TIM and then log back on from time to time throughout the day to check for him)

So, you fight all the way to the end and there's nothing there.

Is this "working as intended"?