Service Agents availability shows 8 hours per day without having any Time Model assigned to them.
Reproducing the Issue
1. Go to the Resource Management work center
2. Select Resource Profiles.
3. Search for any Service Agent.
4. Select Edit.
5. Navigate to the Tab Availability
6. Select Resource Availability.
It is standard system behaviour
For any Service Agent it is not possible to assign Work Schedule and hence all the Service Agents are by default assign with the availability of 8 hours per day.
KBA , SRD-HR-RPM , Resource Pool Management , How To