Where does mistakes come from?
Mark Bernstein discusses mistakes in design, but his comment holds true for other types of mistakes in connection to planning:

Second, it's probably wrong to assume that mistakes arise only because people weren't paying attention, or didn't care, or were conceited, self-indulgent idiots. Mistakes arise because people were avoiding other mistakes, because they were trying to save your time and money, because they're human.

This semester has been more than usually rough. While I have been working on the final chapter in the PhD, I have also been redesigning the Public Information Study at Volda College to adhere to the "Quality reform", the large and very dramatic reform of the educational structure at College- and University-level in Norway. This is a process of high insecurity both for the staff and the students. The students are aware that the study they applied to might not be the same that they actually enter and have to go through with, and their insecurity and following aggression is directed towards the closest target - their teachers. We, the same teachers, are trapped between the orders to commit to the structural changes, and the structural changes themselves, which for instance includes a change in the funding.

Rather than being paid according to how many students we take into the study, we will get paid according to how many actually take an exam here. This is problematic for several reasons. Connected with the liberalisation of the asessment system, which now permits us to not use external assessors, it can influence the quality of the students we send out. But it has a more immediate effect: We won't get funding for the students we have now until a year after their exam! That means that all initiative at this end has to happen on pure idealism and faith. We can't expect to afford equipment or more staff to cover for the increased burden of administration until two years after we have started a one-year course. This means short, quickly finished courses, which is the opposite of the pedagogic goals of the quality reform. The reform idealises frequent feedback over a long period of time in order to emphasis maturity and development rather than fragmented courses and small exams.

We, the teachers, are trapped in this, between the fear and frustration of the students and the experiments of the Ministry of Education. And we make mistakes. We try to avoid one problem, so we make another. We try to protect one group of students, and so we hurt another. All our excellent intentions come to nothing, and despair is close... And we don't do these mistakes because we are idiots or deliberately evil. We make them because we are trapped, and human.