Some scholars also talk about “the Goldilocks principle” of getting things ju...st right. The earliest references that I know are from:
Katz, L., & Raths, J. (1985). A Framework for Research on Teacher Education Programs. Journal of Teacher Education, 36(6), 9-15.
and:
Silverstein, M. (1987). Monoglot “Standard” in America: Standardization and Metaphors of Linguistic Hegemony. Working Papers of the Center for Psychosocial Studies 13.