Many of the agency employees will changeover between the various agencies to work in different roles. Field staff will very often transition to account or other internal positions on the agency side. Meanwhile, agency workers will move over to the client side of the business. While not as frequent, both client and agency personnel do switch over to the field as well. Since the industry as a whole is mostly run by small-scale agencies, new agencies spring up every year lead by the same people. Fostering the right relationships can catapult your opportunities. Conversely, burning even one bridge has a high likelihood of coming back to bite you sooner than later.