Roomba can clean all of the debris with one pass over each area. However in some scenarios (e.g. homes with pets), it may take multiple passes to clean up everything. For this reason, you have the option to set Roomba to complete two passes, rather than one.
The default setting is automatic. Roomba intelligently chooses to use two or more passes for a single small room or one pass if cleaning a larger space. This setting can be helpful for those who Roomba in varying sized spaces. When placed in a smaller room, Roomba can choose to do more cleaning passes without concern for battery depletion. Use the iRobot HOME App and select 
Cleaning Preferences ➔ Cleaning Pass to toggle cleaning pass settings.
Automatic cleaning preference is available with the following software versions:
iRobot HOME App: 1.5.1 or later.
Robot Software: 1.6.6 or later. To check the robot's firmware, open the iRobot HOME App and select 
More ➔ 
Settings ➔ About (Robot Name). Roomba will automatically update its firmware if a new version is available when it's connected to your Wi-Fi network and is on the Home Base.
Additional Cleaning Pass preferences are compatible with the Roomba i Series and Roomba 900 Series Robot Vacuums.
