I'm reading the core book about the mechanics and I see that a Success threshold of 4 is supposed to be challenging. Here's the exact wording.
The standard threshold is 1 (so only 1 hit is necessary to succeed), though other tests may have thresholds as high as 4 or more.
It doesn't sounds that high when you can easily have 15 dice in your pool. The table says that 4 is hard and 6 is extreme but on forums I read that a Troll with a bow can shoot at 900m with a -3 penalty to dice pool pretty easily...so so where can I find examples of threshold if shooting an arrow one kilometer away seems to be easy?