Originally Posted by MisterB

Those are common areas where some people experience difficulty, yes. Traveler's Vale can be challenging when you first arrive at Yak's Bend, and if you take all the quests available. Most of the quests there spawn additional monsters in the zone, so taking all of them makes that zone a bit crowded.

Black Curtain has the overlapping patrols with a constant speed increase. The Necrid Horsemen can raise minions, so a party can be overwhelmed if it takes too long to defeat the group, or allows too many minions to appear.

Aggro control, identifying patrol patterns, pulling, and proper targetting solve all of those problems.