When choosing the location for the camera it's important to choose one where no foreign objects intrude into the frame (gutters, balconies, beams, etc.) and the camera isn't tilted too much towards a wall. You'd then create so-called "burnt-out spots" in the scene. These spots will be intensely lit by IR illumination while the rest of the frame goes dark as the shutter compensates for these extreme differences. The image then becomes poor and grainy. WDR can deal with this to a degree, but if the difference is large the only solution is to change the camera position and aim.
Below is an example of an incorrectly placed camera where the nearby wall and beam create "burnt-out spots" and the IR-range reduction effect described above. The solution is to angle the camera away from the wall and the soffit.
