@lalanc01 , in most cases you can leave devices in an older feature update profile. When a device is in multiple policies, the system will identify the policy with the latest update and use those settings. If you have a device in multiple policies with the same update, and otherwise different settings, that will cause a conflict and an alert will be raised in the Feature updates failures report so you know which devices are affected.
However, having devices in multiple policies can be confusing when you are reviewing your own policies. As a result, having devices in one Feature update policy at a time is a good idea.