I teach a wide variety of grades.  I'm in a small school that has middle and high schools combined.  I teach 6 grades.  So, having pre-made materials that I could print and sort by student made it easy for me to stay organized while working with multiple students on multiple grade levels, ability levels, and subjects all at the same time.  This same binder system also eliminated the need for substitute lesson plan preps as my paraprofessional and the sub were able to easily see where each student was at that moment and continue instruction.