I might as well add my 2 cents on NATE and training.
I have done training the last 7 years. I have found there are good young and older techs. There are some not too good young and older techs. There are people who can learn in seminars and some that use field experience as their seminar. The only down side to learning in the field is when being taught by others in the field and you also learn their old bad habits. The classroom will teach the proper way it should be done. That does not mean it is the only way to do something. An instructor should teach the whys of why something is done not just how. Take a look at the idea of pumping away from the expansion tank. This came about almost 50 years ago. There are many who do not do it today. Return side circulators may have been the way they were taught or the way they always have done it. An instructors job is to teach why it must be moved. The circulators have changed, so old 3 piece circulators removed air with water volume and the wet rotor pumps must do it by adding pressure to the system. If the instructor just says it must be moved the why was not answered.
The industry is changing so rapidly today we need schools to keep up with the changes. I see in my classes some people do not apply what they learn when I need to visit the problem job site after the class. The class gives you the basics and a better understanding of how it is supposed to work but no school will take the place of, after learning the basis building you own troubleshooting skills and fact finding missions.
Very well put.