I interned at a big commercial studio in philly, and I'll tell you from my experience it's definitely worth it. The downside, at least, from my experience was that they really didn't give two shits about me at all. Gain all the knowledge you can while you're there because it's really all about the money for them. A commercial studio really is the best place to learn, but I found that a lot of engineers there would cut corners and use methods that I thought hurt the music, like the hyper-compression, excessive grid-snapping, a general disinterest in their work, and disregard for their client. Basically it was all about speed and just relying on the "technology" where I was, it had little to do with listening and making creative, well thought out, musical, decisions. Of course, every client and engineer would be different, but that was the general vibe I got there over a year and a half of work. It was kind of bittersweet when the owner asked me, "what is it that you do here?" After a year of cutting my teeth and running around like a crazy person trying to please everyone. It was bitter, because it's hard to find a job in the industry and this was my foot in, but sweet because that place kinda sucked! Anyway, I've been loving the music I'm making right now with a lot of the knowledge I learned there. The best skill I learned there however, was how to clean a toilet !