Generally, the guidelines suggest that you don't isolate someone without contact with people when you're trying to prevent and manage suicide. So if you're talking specifically about suicide, the level of risk should indicate the level of supervision that somebody receives.
The literature is very clear that isolating someone who is at potential risk for suicide is a contributor to the completed suicide. So staff interaction every 15 minutes, or every five minutes, and not replacing direct and meaningful staff interaction with technology, such as cameras, or with other correctional inmates who often serve as companions—