I would tend to conditionally disagree. If you are planning on getting into commercial work especially. While skill and knowledge has little to do with schooling (or lack thereof). What it will do is give you solid, theory based tools to make your work better. It does create good work habits, and gives you the tools to think critically about art in general, as well as photography, which helps define and refine you compositional and color theory skills. In addition, you have a common, consistent and defined skillset that allows you to accurately and effectively communicate with AD's, designers and the like.
Originally Posted by 2F/2F
I felt like a lot of the others here, and it wasn't until I was in school for a couple of semesters that I realized it had changed not just my compositional skills, as well as being more aware of the interplay of light, but also the way I assessed my own and other's work changed dramatically. Granted, I'm not 18 anymore, and it's been a few decades since I was, but I can say that if you apply yourself to it, it will change you as an artist, refining you.