Job centers are only one option to find job listings. Internet searches, newspaper ads are other viable options. The key to using job centers is that you will need to visit them daily. One day the job you are looking for could turn up but be snapped up before you have a chance to apply for it. However some job centers will send out an alert when a certain type of job comes in, but you should do the leg work yourself to stay on top of the postings. As I said, you don't want to miss out on that one job that will meet your expectations. Don't solely rely on just job centers, though. The internet is one of the best ways to do a job search, and that is where you will find the better jobs.