A scent delivery system includes scent delivery units that are configured to deliver scent at a variable scent level by being turned on and off successively according to a variable duty cycle. The scent delivery units are associated with corresponding base scent settings. The scent delivery system also includes a central controller configured to control the scent delivery units by generating command data based on a scenting schedule that indicates a desired activation time for more than one implicated scent delivery unit. The scenting schedule is configured to further indicate a scent level bias to be applied to the base scent settings that are associated with different of the implicated scent delivery units. The central controller is configured to generate the command data, based upon a variation in the scent level bias, that takes into account a corresponding variation to duty cycles that are associated with different of the implicated scent delivery units and to communicate the command data to the different implicated scent delivery units.