Hello @Menta Elise
The "Software Updates deployment evaluation cycle" triggers in the background the Windows Update agent to scan with the Software Update point the updates, which SU is installed/missing, then the WUA starts the deployment of missing updates within the deployment parameters configured.
how often does it run, and when should it be executed manually?
By default, this scan uses a simple schedule to start every seven days, you can customize it under Client Settings > Software Updates. But sometimes, for troubleshooting purpose, you may need to run it manually from the Configuration Manager from the Control Panel.
For more details:
- Clients Settings - Software Updates
- ConfigMgr Software Updates Deployment Evaluation Cycle | Client Action
Regards,
Youssef Saad | Blog: https://youssef-saad.blogspot.com/ | LinkedIn