To a significant extent, flexible learning is quite inflexible in the sense that mistakes incorporated into learning resources cannot easily be corrected; the teacher cannot simply tell students at the next lecture or tutorial or easily issue corrected material. [...] as explained in Chapter 2, the process of managing, producing, and editing material is labour intensive, painstaking, and, thereby, expensive.
Watson, R. (2009). Book review: Flexible higher education. Review of higher education, 32(3), 437 - 439