I worked for two Schools that attempted a mentoring program for instructors, both were relatively successful by creating a team leader grade one who acted as a guide for the less experienced. Unfortunately it was entirely pushed within the pilot group and not from management. So mostly fell apart when the lead instructors who set it up left. There were a lot of benefits from the system not the least being standardization and a reduction in training times as you had a group working together with students rather than individuals. I remember a lot of discussions about weather, both dangers and appropriate conditions for training, when students should go solo etc etc... During the program we never had a weather related incident or many incidents at all except a few students doing absent minded student things... It also made solo checks and tests very easy as having a group working together on a student really covered all bases and also made it easier for the student to transition to flying with others as they were not so hung up on the next instructor wanting something different from them.
Sadly my long term in GA only proved to me that no GA company was interested in being better, just getting more students/cash etc...
Even to the point where at one such employer having a group of instructors together talking about their students was considered wasting time when they should be flying.