Funny, we are getting into this, albeit for different reasons. My soon to be 16yo has been seeing a Therapist about elbow pain, and the PT has determined (he is also a pitching guy who has worked with Team USA, and MilB and MLB players) that my son has to revamp his motion. Basically, he said he was using too much arm and not enough of his strong body. He wants to see a longer stride, among other things. It's hard, because son has to break old habits.
PT's mentioned that he wants my son to get a tired core, legs, and shoulder/back, not a sore elbow.
In our case, the longer stride never would've happened if he hadn't gotten help/training, and it is still a work in progress. I find that most pitching coaches just deal with what you bring and make small adjustments. They don't want to completely change things.
Having said all that, pitching is intensely individual. There is no "one size fits all" advice.