Catatonic patients can be dangerous for reasons most people overlook. They could become frozen in movement to a degree where because of their lack of action, no one notices them, and as a result they might not be performing appropriate ADLs. The lack of movement could also result in muscle breakdown leading to possible renal failure.
Anyone suspected of catatonia needs to be carefully observed. Because this phenomenon is not common, most staff don't realize that a catatonic patient not creating any attention could actually be dangerous because their mindsets are wired by experienced to look out for the patients that draw attention. That's a reason for 1 to 1s.
Whenever I have a catatonic patient, I go through a little 5 minute lesson where I get all the staff members and remind them what it is, and why we need to worry about the possibly catatonic patient even if they're not drawing attention. I do that because I noticed on other units, the psychiatrist often doesn't do it, and when I reviewing those cases for court, I'm sometimes amazed the patient didn't go into renal failure---dumb luck.
When you got a phenomenon you see often, you remember it. When it happens only once every few months to even years, that's different.