Can a worker turn StaffCounter off for some time?

Yes, it can. Even without administrator rights, an employee can open the program and stop monitoring. However, after rebooting, StaffCounter will automatically start again.

If there is a StaffCounter icon in the menu bar (and in the case of a cloud service, there is one in any case), then, using it, an employee can temporarily disable monitoring for an hour or half an hour, depending on the version. After this time, monitoring will resume automatically. In addition, there is a command to completely stop monitoring.
In this case, the activity log will contain the entry “Monitoring stopped by the user” or “Monitoring paused by the user”.