The cedar will absorb some of the aroma in your humidor, while adding the "natural" or "desired" spanish cedar aroma. Therefore, if you place additional strips of cedar in your humidor, they will absorb some of the unwanted aroma. Later on, after the unwanted aroma is minimized, or gone, you can remove these strips, as they have done their job.
You can also do this as a quick fix when your humidor has too much moisture.