We have people working on shift rotation for 24/7 coverage.
Given that we're always tight on people, it's always a mess to re-arrange things.
I've looked into this and the so-called "nurse scheduling problem" is not trivial at all.
Then if you also take into account preference of the shift workers in terms of other shift workers, some absences here there (PTO and/or sick leave), various arbitrary non-technical constraints (we have a couple of "peculiar" human cases)... It gets messy.
Quite hard to automate, but feasible by hand.