I consider that the first choice (teachers' mediation and assistance, if I understand well) is the case, regarding the main question of the discussion thread.
The ultimate goal of the use of educational props or scaffolds is to become self-reliant and independent in the performance of the learned task or other meaning transfer the responsibility of accomplishing the task from the most experienced (teacher or peer) to the learner, that is to become a learner functionally in the performance of the activity or task, rather than following the guidance of others, the most important element is the learning program that links the teacher to the student.
The background of the recipient is different, so the methods are integrated with different student situations and teaching methods, and with different course quality
It depends on the student's level of trust. If the student is comfortable with the teacher than (s)he will be more receptive of what is being communicated by that instructor. If the rapport is not there and the student is uncertain about the material (s)he is learning a trusted peer, relative, or friend who understands the material and is able to communicate what (s)he knows would be more helpful. Children who have suffered trauma are more skeptical of adults and are more comfortable learning from someone they have a trusted relationship with.
La formación terciaria es altamente profesioalizante y ene se contexto, debemos de considear el desarrollo de habilidades laborales en los estudiantes en que la autovelauación y el trabajo en quipo son necesrios. Y alli el proceso que incluye la evaluación entre pares (coevaluación) me parece un insumo que debe ser incorporado de forma paulatina en el proceso formativo.
I think the best answer is that both are important and are necessary. The whole Idea of scaffolding (or mediating in other ways) is to ensure increased comprehension of the principle(s) and a clearer understanding of the significance and/or importance of the principle(s) that are comprehended. Having the assistance of both one's peers and the teacher should help with this process...and the two perspectives underlying the scaffolding will be beneficial.