I'm not a big fan of the "form a committee" approach to problem solving and the system you propose is far to open to abuse. To track the performance of apprentice pilots we need slightly more formalized approach flight training, one way I would suggest is a standard system of training cards cross referenced with the relevant syllabus, many professional schools will no doubt want to exceed the standard set by the syllabus but the base line has to be set and seen to be achieved.
For a good description of the role of an instructor have look at the introduction in the flight instructors manual.