Other students prefer to take breaks. Either way is acceptable, as long as the task is completed. Certain individuals prefer to eat while learning. If the student is that type of learner, have food or drink readily available in the practice area. This way more time will be spent practicing than traveling to the refrigerator.
Many students learn best while working with others.
An ideal way to develop a sense of musical ensemble may be to allow students to work together. Some students prefer to self-structure practice sessions, others prefer imposed goals and rewards. Most music teachers recommend a way to practice between lessons. Parents of students who need imposed structure should reinforce the teacher's suggestions. Students who prefer self-structure can, and should, adapt the suggestions of the teacher to become their own.