Shifts normally have staff members assigned. There are some special shifts that do not have a staff member listed.
Extra shifts are available for any staff member to take as long as they have the same skill/role assigned as the shift. Other limitations and restrictions can apply including venues, hour limits, enforced rest and more.
These shifts are not available for staff to take themselves and must be manually assigned to the staff member. This is done in the same way as transferring a shift between staff members via Shift Week, Shifts Grid or Shift Timeline.