Aint that the truth! I know this is an old post but the collage system (except a few schools) breeds and perpetuates ignorance.
If these collage/HS coaches really cared about improvement they would be investigating the training methods of standout athletes because often times if you get a standout athlete you will find that the bulk of there training history was under the guidance of there parents or club coach.
Angela Williams (Father/So Cal cheetahs club), Kevin Jones, NFL player,(his dad trained him), Walter Dix (father) Obea Moore (LA Jets), and other people who I could list but you might not know who they are were NOT trained in the system for the bulk of there sports careers.
BTW, Angelia Williams and other people from USC would train under the same club coach I was with (I would practice with them) but then go and compete for USC. Literally, they would drive 30+ minutes each way in LA traffic just to get to practice where this club coach was…
In regards to the rest of the topic, I feel if you have the best possible training methods, with dedication you can coach yourself to a high level (if you have the basic talent) however you need to be able to go into yourself and “feel” if you need to stop a workout as well as look for signs of overworking such as muscle spasms, flickering eyelids and a depressed state of mind.
I literally train my recovery just as hard as I train on the track so I have never had any major injures due to the fact that I give myself time to mentally and physically recover.
Once you get to an elite level I do feel a coach is needed along with a host of other people to preform massages, strength/gym work, and preparing meals so you can get that extra 5-10% extra out of yourself that I just don’t feel you can get on your own.