College interns can provide significant value and productivity gains for employers. A study by The Internship Institute found that a single manager can gain the equivalent of 225 full workdays per year by supervising 4 interns working 15 hours per week each. While requiring around 10 hours of supervision per week, interns completed an average of 60 hours of work. This resulted in a net productivity yield of 1,800 hours or 225 workdays annually for the supervising manager.