I was going through my last TI training session and recalled an important moment. I remarked to my coach that many swim coaches tell you what to do, or describe something to you, but it never seems to work. I never seemed to improve enough with what advice I get from them. However, in the 3 lessons that I've had with my TI coach, I've improved so much, probably more so than in the years I've had going to Masters swimming.
He said something very insightful in reply, which was that a lot of coaches forget what it was like to be a beginner. They only know the present, which is at a high level of mastery of the skills and they attempt to describe that mastered state to us beginners, but we miss what it took to get to this state. Thus, we have little knowledge on how to get there, but only a description of the end result.
Total Immersion attempts to capture and teach the journey to mastery of swimming, and thus we do a lot of drills and exercises which may seem to be ridiculous to many, but there is a purpose behind doing these drills, and practicing and isolating the various elements of swimming mastery.
I find this to be true for coaches in all aspects of triathlon as well. I had a friend who was training with a pro-level coach, and he gave the whole group a training program that was based on HIS level of mastery of cycling and running. It was a program that was too advanced and assumed a level of skill and fitness which was not necessarily everyone's level. This is bad because you may push someone to do something that they're not ready for, and ultimately dissatisfaction for the sport and injury can result.
The best coaches are those who remember what it was like when they were just starting out. They remember AND can bring newbies on the journey to mastery of the essential skills of swimming, cycling, and running. Stay away from those who are insensitive to your current skill level, and treat all of their athletes like pro-level athletes. Working with these coaches puts yourself in danger of hurting yourself and inevitably cutting yourself short of the physical achievement you might get working with someone who is more sensitive to your individual needs.