You should use a VPN when:
You do not have access to a home computer, but could bring your work laptop home. In this instance, you would use Cisco AnyConnect VPN to access secure systems such as ROSI and AMS/SAP.
You have your U of T computer at home, but you need access to your I: or H: drives. In this instance, you would use UTORcsi.
You need access to specific departmental shares.