Looping can flourish on any scale, from two interested teachers in self-contained classrooms to an entire school system. Looping can be used from kindergarten through high school, but in the U.S. it is most common at the primary and middle-school levels. Each Waldorf School teacher remains with one class throughout grades 1-8. Opinions differ regarding when the advantages of variety outweigh the benefits of stability and indepth relationships. The point at which the balance tips may depend on the characteristics of a school's students, staff, and community.
Longer contact can amplify the negative as well as the positive aspects of relationships.
The greatest concern of parents is that their child might spend two years with an ineffective teacher. Time can also exacerbate problems with student-teacher personality clashes, unreasonably demanding parents, problematic mixtures of students, and specific weaknesses of a generally good teacher. Simel reports that joining a looping class is hard on newcomers, and that introducing five or more new students in the second year can be disruptive enough to reduce the benefits of looping for the original students. Some students and teachers also experience emotional difficulty leaving their classes at the end of a loop. Looping's longer time-frame increases motivation to resolve problems that might have been ridden out for one year.