From an old HBR article on generalists:
Professor Phillip Tetlock conducted a 20+ year study of 284 professional forecasters. He asked them to predict the probability of various occurrences both within and outside of their areas of expertise. Analysis of the 80,000+ forecasts found that experts are less accurate predictors than non-experts in their area of expertise. Tetlock’s conclusion: when seeking accuracy of predictions, it is better to turn to those like “Berlin’s prototypical fox, those who know many little things, draw from an eclectic array of traditions, and accept ambiguity and contradictions.” Ideological reliance on a single perspective appears detrimental to one’s ability to successfully navigate vague or poorly-defined situations (which are more prevalent today than ever before).