For schools, the answer lies in Education Code 51769(b). To be a job shadower you would need to spend between 3 hours and 25 hours exploring a career at the workplace. More than that and you risk becoming an intern….
Education Code 51769
(b) For purposes of this section, "job shadowing experience" means a visit to a workplace for the purpose of career exploration for no less than three hours and no more than 25 hours in one semester, intersession, or summer school session.