About a month or so ago, the referral agency that provides me with students sent along a new potential student. This was a 61-year-old man who had been having lessons with another teacher for several years but she was leaving Japan and he needed a new teacher. The agency had sent him to another (male) teacher but he had corrected his pronunciation "too strictly" and the student had rejected that teacher.
One of the plethora of things you learn early on while teaching Japanese students is that they won't like you unless you use a soft touch when correcting them. It's okay to correct frequently (if the student desires it) but not okay to do so sternly. I'm not sure if the teacher who preceded me was inexperienced or oblivious to this fact but he alienated my student pretty thoroughly and instilled in him a nagging insecurity about his ability to be understood.
One of the things the teacher made this fellow do was repeatedly count ("1, 2, 3, 4...") to practice pronunciation. Boring, pointless types of practice are generally the hallmark of a poor teacher who has a limited bag of tricks that he or she trots out in order to pass the time in the lesson without actually addressing the short-comings of the student. In this case, if someone has a pronunciation problem, it's in enunciating certain sounds, not in numbers or colors or types of animals. This new fellow's biggest issue is pronouncing "see" and "she" properly. How is counting off again and again going to help him except when he hits the "6" and "7" words? It was a particularly poor choice of pronunciation exercise for a 61-year-old man capable of discussing politics and social issues to be reduced to elementary school recitation exercises. I'm sure he was humiliated.
Unfortunately, the fact that most people come to Japan and stay for a short time and the fact that teaching English is seen as a crappy job which is regarded with disdain by those who have moved on to other work keeps Japan populated with people in the English language business who don't know what they're doing. The former simply never get enough experience to be good at it and the latter think it isn't the sort of thing you need to be good at (or even can be good at).
You find that the vast majority of teachers are spending their lessons teaching what is easy for them rather than what is useful for the students. When I was at Nova (15 years ago), we were mainly teaching 40 units of American Streamline per level. The teachers weren't trained in how to teach the grammar point of each lesson nor were they given sufficient time before each lesson to review the teacher's text (when they had one to work from). The student information sheets had a list of numbers, 1-40, and you marked off the lesson you did so another teacher wouldn't repeat it with the same student. When you got one of these sheets for a student who was stuck at a certain level and couldn't advance to the next, you'd find that the student had repeatedly done the same lessons with a lot of reading content again and again and had never done the ones with very little text to read. The reason for this was that inexperienced teachers would waste class time having students read aloud rather than practice the lesson points in a meaningful way. This meant less work for the teacher both in terms of preparation and imagination. Since Japanese students grow up in a school system which emphasizes rote memorization and often repetition to that end, they don't even realize how crummy the lesson they're getting is in terms of helping advance their English skills.
Teaching well is very challenging and generally unrewarding in terms of how you are regarded by fellow foreigners (who love nothing more than to climb on their high horses and look down on the English teaching rabble they've scrambled away from to their Japanese office jobs) or by the Japanese students and employers who believe what you do is a doddle because you speak English already. While a student may benefit from your skill, she tends not to realize that it is extraordinary in nature. Most students generally can't tell the difference between the gaijin monkey who fills the lesson time with pointless games or prattling about himself and the teacher who is working to improve the student's weak points while still making the lesson interesting.
All that being said, a few of my students have left teachers and language schools specifically because they felt they were getting nowhere. One of them recently told me she'd started doing a conversation exchange with a British friend and that she realized from trying to deal with his Japanese that it was extremely tiring. She wasn't even teaching him but just focusing on his mistakes and correcting them was exhausting for her. After this experience, she told me she really respected what I did. I must say that that was an immensely gratifying thing to hear as it is all too rare for anyone to spend time in my shoes.