If you use AdRoll, you may not need to use Facebook's separate retargeting, as AdRoll integrates Facebook retargeting into its platform. AdRoll allows you to run retargeting ads on Facebook alongside other channels like websites and email. This gives you a centralized platform to manage all your campaigns. However, Facebook’s native retargeting may offer unique features or insights not available through AdRoll. If you prefer detailed control over Facebook-specific campaigns, you might still consider using Facebook retargeting directly. For a streamlined approach, AdRoll can handle Facebook retargeting effectively as part of a multi-channel strategy.