Disk usage checks should be configurable in the sense that it supports escalating priorities. For instance, usage >70% raises a warning alert, and if not resolved and disk usage reaches >90% it escalates to a critical.
I currently have two disk usage checks configured on policies for both servers and workstations to reflect this. Both show on workstation, and only one of them shows on server. I am told only a single disk check is supported and while originally my bug report was for two not working, I think the better overall solution is to rework the single disk check policy to include the escalations.