I don't use Screen Time but maybe these document sections provide some clarity?
App Limits
Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support
"You can set daily limits for app categories with App Limits. For example, you might want to see productivity apps while you're at work, but not social networking or games. App Limits refresh every day at midnight, and you can delete them any time."
Set up parental controls with Family Sharing on iPhone - Apple Support
Customize parental controls during setup
When you add a child to your Family Sharing group or set up a device for a child, you can customize parental controls from the start. You can change those settings at any time.
- Downtime and limits for specific apps