How often do I need to login using dual factor?

This depends on what you are doing, how you are doing it, and if you are a student or faculty/staff member; Portal will remember your dual factor on each browser you login to (i.e. if you dual factor on your computer using Chrome/Firefox/Internet Explorer you shouldn’t have to dual factor again for the day (if you are a staff/faculty member) or week (if you are a student) as long as that same browser and device is the one being used).