Drill holes can be very unpredictable in the path that they take, so drillers often have to deal with hole deviation.
Drill hole deviation is when the hole ends up going in a direction other than the chosen trajectory.
The installation of the wedge is done easily in a few steps.
Multiple factors can play a role in causing this to happen, such as rock formation in the ground that you are drilling, the type of bit used, the weight on the bit, type of rods and tooling, the set-up of the drill rig and its location, among others.