I don't do Schutzhund...but its because of the time thing. The closest club to me is about an hour away. So every Sunday I would be driving there an hour and back an hour. On top of that, you're probably going to be there all day because its not just a "train my dog and leave" type of thing. You stay around, learn from more experienced people, help where you can, ect. Then throughout the week you need to work on things at home (not crazy time commitment, but could be if you decide you want to trial and get as many points as possible). Someone else can tell you about the exact time requirements but I've done some tracking work and even a short track takes about 30 minutes to lay down (and imagine doing that on a weekday).
I was extremely interested when I got my dog, but realized I didn't want to or have the time to commit to this. It does become a hobby and I applaud the people that do it. I have my own hobbies that at this point in my life are a little more important to me than Schutzhund, and at the end of the day that is probably what keeps me from doing it (I like my 18 holes on a Sunday).
The closer the training area is to your home, the better though. But make sure you get a lot of references on the instructors and the helpers. I've heard from more than a few people that there are some you want to work with, and other you shouldn't even let look at your dog.