Ongoing and regular two-way communication between coach and athlete is important.  A coach may have expertise in the generalities of training, but ultimately only you know what is best for you on a given day.

Challenging, clear goals are necessary for improvement. Our coaching is based on goal races and times

Commitment to personally meaningful goals is the path to success.  While a coach can help you articulate goals, you are ultimately responsible for setting and achieving those goals.

Its not necessary to time workouts to the second or measure all distance to the yard. Heart rate monitors have their place, but mostly they just validate experience. In short, what you do in training should have a basic scientific basis, but its more important to understand what you are doing on a common sense basis and believe that it will work. 

Change and experimentation is good, but radically altering your training pattern every six months based on the latest and greatest "scientific study" is not good.  There are certain time tested training principles that should be included in every program.  (See the Five Iron Laws of Quick Running.)

Monitoring and feedback is needed for ongoing improvement.  You learn what is best for you through trial, error, and success.  Knowing what doesn't work for you is as important as knowing what does work for you.