Helps to put the student in the right frame of mind for studying. Certain times of the day become associated with studying. Forces the allocation of time for various needs and desires and helps to establish priorities. Helps to condition others to your needs and encourages them to work their expectations around your schedule. Studying is hard work and implementing a schedule is hard work.
Few people become good students just as few people become good managers.
Successful people are in part successful because they manage their time carefully. Schedules must be specific and detailed to be successfully implemented. Most people do not plan their schedules in sufficient detail. For example starting time, quitting time, and break time need to be specifically indicated. Objectives must be realistic.