Not sure what level of content you're looking for and what reason, but I'll give it a go. The Heart of Thorns maps (apart from Dragon's Stand) all follow the "event chain" model. You can see the tower icons on the map to find where the event currently going is. After you complete a chain, there are normally a few more harder events afterwards. I'm not sure I'd consider them fast if the goal was just number of events. This is also true for the "mini zones" in the SotO maps. There's an event in Thunderhead Peaks (in one of the puzzle rooms) to kill 1 elite that can be spammed over and over again (easy way to finish the Return To achievement)