Integration Vs Expertise

What is the best way to look at a campaign? Has one consultancy manage the end-to-end execution or bring in specialists to manage each unique part of the campaign that is best suited for? Do all integrated firms have expertise all across the value chain? Can they provide the same results as multiple independent experts can bring to the table? Do Independents have the expertise of understanding the whole piece and effectively aligning to the 360-degree campaign? These are some of the things that bother brand managers and marketers, while there is no one right answer, but here are few points to consider, while planning your campaign