This achievement is more manageable than the ratio indicates. The Slums will typically be more windy and make you do sudden turns so you will have to pay attention to your map at all times (hence the benefit of replaying the challenges). Do the Old Town ones first, they are easier in my opinion and will get you more into the free running mechanics of the game. I found the best way to do this is to get your agility high enough to have the two speed boosts and etcetera. Please note, some locations actually do not penalized you as hard for taking that extra second or two to make sure that jump you're about to take is correct. On your first couple tries, you will likely fail but you will see where you need to go.
The night solution includes many videos and etcetera that should help but basically clearing the areas at night will take clearing them during the day so that you know where to go.
Noticed there was no true guide on here for this so here is my best advice on how to clear on this.
