I am asking if the "coaching class" part of the question https://academia.stackexchange.com/q/16596/546 is on-topic on our site?
In case you have no idea what this coaching (tutoring) class is about, please allow me to explain.
In my location(Taiwan) and many countries in Asia, graduate school admissions are based on entrance exams which consist of written exam and oral exam. In order to pass the exams, many students go to the coaching schools to learn how to succeed in those exams. The coaching schools are more like tutoring schools, or should I say, actually unofficial universities. The coaching schools teach or re-teach the students how to solve the problems they get in the exam. For example, almost all the science/engineering graduate schools will have the test for Calculus or engineering math. The coaching school teach the students how to solve the problems the student may see on the tests, e.g. how to prove the Fundamental Theorem of Calculus. In case you wonder who teaches those coaching classes? The answer is: many of them are unemployed PhDs.
As far as I know, the coaching schools are popular at least in my location. I know they also exist in other Asian locations(I just don't know how popular they are there).
We do use GPA and recommendation letters. However, the recommendation letters are somewhat inflated. GPA is for reference only. Every school may have different standards when grading. The entrance exam is what most people here consider fair.
Thus, the coaching schools are common and popular. There are also coaching schools for taking TOEFL and GRE. I, for one, went to a coaching school and passed TOEFL and GRE 40 years ago.
I personally think coaching classes(schools) is on-topic here. At least, it's not undergraduate only topic. I don't know if it is primarily opinion-based. Please let me know your answer.