Forget broadcast networks. Think social networks. With Procter & Gamble committed to saving $10 billion by 2016 and cutting $1 billion from its marketing budget during that time, the company is determined to spend less on advertising. According to Marc Pritchard, chief marketing officer, P&G, those cuts will come by thinning the ranks of marketing executives and spending more efficiently, leaning more heavily on lower-cost digital marketing and easing up somewhat on pricey broad...