Between magazines and the Internet, there is a ton of information on endurance training to digest out there. Some of it is very beneficial. Most of it causes confusion, mistrust in your present "way", and controversy where controversy may not be ideal.
I have seen many different trends in the sport come and go. Right now we are in the "coaching phase". Everyone is either a coach or has a coach or is their own coach. I know, it's confusing.
USAT came out with a certification process that is supposed to add credibility to the sport, but in my opinion actually diminishes the credibility. It's become more of a bureaucratic bs certification system similar to personal training certifications, putting out lot's of "certified" people who aren't really qualified. This drags the whole field down. I've dealt with it for a long time with personal training - tell most doctors that you are working with a personal trainer and they cringe. Now, I'm witnessing this same effect in endurance sport coaching.
The best is the triathlete that's in their local club (i.e. they have a network to reach to) and trained themselves to some halfway decent results and the next thing you know, they have a website and some clients. Then there are the athletes who have one coach they have worked with for a month, and they read about some great results that some other athletes working with another coach are getting and they jump ship, thinking that besides hard work, there must be some secret training scheme that will get them to take 4 hours off their IM pr in the next two months. I was contacted recently by a guy who was interested in my coaching services. He mentioned that he's been working with a coach for a few months. I asked how his progress was going, to which he said "great". I then responded "so you have been working with a coach for just a few months and you are making progress and you want to switch?!"
I also love seeing certain coaches that prescribe to one way of training. No matter who you are, you must train this way if you want results.
There are lots of great coaches out there - those that have studied hard and built up knowledge through years of experience and working with athletes, not being an athlete. It does seem though that for every great coach right now, there are four posers. I know some incredible coaches who aren't great athletes themselves, and I know some great athletes who attempt to coach and aren't so great, to be nice, at coaching.
Many age groupers look at what pros are doing and what the pros coaches are prescribing and want to emulate this. Keep in mind that A. most of the pros were very fast before working with a coach and B. these same pros have much more time to train - it's their job, so what works for them isn't necessarily the approach an age grouper should take.
The bottom line is that great results come from hard, consistent work. From trusting a plan and staying the course. From being patient. from paying your dues.
If you are in the market for a coach (I'm not promoting my business, and I currently am full anyways) do your research, make sure they have some solid experience, and trust who you choose. Give them at least a year. Remember, it's important to establish a relationship.
Above all, make sure that they are aware of your goals and that the two of you set up a realistic plan that fits into your lifestyle and challenges you.